Teenage phenomenon Coco Gauff says she will go into her Australian Open last-16 match against Sofia Kenin with a “huge” confidence boost after beating 2019 champion Naomi Osaka.

The 15-year-old American will reach her first Grand Slam quarter-final if she beats 14th seed Kenin on Sunday.

Roger Federer takes on Hungary’s Marton Fucsovics, while defending champion Novak Djokovic meets Diego Schwartzman.

Australian world number one Ashleigh Barty plays American Alison Riske.

Relaxed Gauff enjoying having ‘more fun’

Gauff has become a global star since announcing her arrival with a victory over seven-time Grand Slam champion Venus Williams at Wimbledon, where ‘Cocomania’ ensued as she went on to reach the last 16.

The Florida teenager’s first appearance at her home Grand Slam two months later fell flat, however, as she struggled to cope with the intense scrutiny at the US Open.

That culminated in an error-strewn performance in the third round against Osaka, who warmed hearts by consoling her young rival when Gauff broke into tears after a one-sided defeat.

The pair met again at Melbourne Park on Friday, Gauff responding with an assured performance to beat an out-of-sorts Osaka 6-4 6-3 in just 67 minutes.

“I learned a lot from that US Open. Not even just playing against Naomi, but the whole tournament,” said Gauff, who meets Kenin at about 03:30 GMT on Melbourne Arena.

“I think I was on edge. I had the three-setters in the first two rounds of the US Open and I think that was just dealing with all of the media.

“I feel like now I’m more playing, just having fun. Winning is a cherry on top, but I’m honestly having a lot of fun on the court, even in those tight situations.”

• Achilles injury stopped me playing doubles – Bertens column
• Where does Williams go after latest Grand Slam defeat?
• How to follow Australian Open on BBC

Will Federer have recovered from Millman epic?

Federer, 38, plays last on Rod Laver Arena against world number 67 Fucsovics, giving the Swiss third seed additional time to recover from his late-night epic against Australian John Millman.

The six-time champion, who last won the title in 2018, fought back from 8-4 down in the final set tie-break to see off Millman after more than four hours on court.

Federer trailed by a set and then led two sets to one, eventually sealing a five-set win at 00:50 local time in Melbourne.

“It’s very gruelling and, at times, very disappointing, that you are in situations where you get broken in the fifth or you’re down in the super breaker,” Federer said.

“That’s when you really start wondering: ‘Why couldn’t I close this match earlier?'”

Second seed Djokovic, 32, has so far looked as comfortable as ever at a venue where he has lost just three matches in the past 10 years.

After dropping a set in his opening match against Germany’s Jan-Lennard Struff, the record seven-time champion has breezed past Japanese opponents Tatsuma Ito and Yoshihito Nishioka.

The Serb dropped just six points on serve in a 6-3 6-2 6-2 win against Nishioka.

“That’s probably as best as my serve can actually be in the moment, which I’m very pleased with,” Djokovic said.

“It allows me to go quicker through my games and win more dominantly my service games and put additional pressure on the service games of my opponents.

“That’s definitely something that’s useful going towards the second week of the Grand Slam.”

Barty out to avenge Wimbledon loss

Barty, 23, continues her quest to become the first home player to win an Australian Open singles title in 42 years.

The Queenslander faces 29-year-old Riske, who knocked her out of Wimbledon last year, on Laver.

Barty has won all six sets at Melbourne Park, dropping just 12 games, since losing the first of her opening match against Ukraine’s Lesia Tsurenko.

“That Wimbledon defeat is a match that I didn’t want to think about really,” said Barty, who had won her first Grand Slam title at Roland Garros a month earlier.

“For me, it was the end of a long trip. I felt like I was pretty tired. It had been a massive few months away from home.”

Elsewhere, Chinese 27th seed Wang Qiang tries to back up her stunning win over American great Serena Williams when she meets Tunisia’s Ons Jabeur on Margaret Court Arena at about 05:00 GMT.

Nick Kyrgios will face top seed Rafael Nadal in the last 16 at the Australian Open after a five-set win over Karen Khachanov.

Kyrgios, who missed match points in the third and fourth sets, won 6-2 7-6 (7-5) 6-7 (6-8) 6-7 (7-9) 7-6 (10-8).

The Australian, 24, needed nearly four-and-a-half hours to win a tense third-round match against the Russian – having led by two sets and a break.

But he came through in a final-set tie-break at a boisterous Melbourne Arena.

“It was definitely one of the craziest matches I’ve ever been a part of,” Kyrgios said.

Kyrgios leads 2-1 in his head-to-head record on hard courts against Nadal, with whom he has rarely seen eye-to-eye, although the 19-time Grand Slam champion leads 4-3 on all surfaces.

The pair, who will meet at Melbourne Park on Monday, last faced each other on grass at Wimbledon in July when Nadal won in four sets.

• Second seed Pliskova knocked out
• Monfils beats Gulbis to reach last 16
• Where does Melbourne exit leave Williams’ chase for another Grand Slam?

The Spanish top seed, 33, cruised past compatriot Pablo Carreno Busta 6-1 6-2 6-4 in his third-round match earlier on Saturday.

The world number one wrapped up a straightforward win almost seven hours earlier than Kyrgios, whose brutal contest against Khachanov lasted for four hours and 26 minutes.

“I’m not thinking about that [playing Nadal] – I’m just thinking about my legs and getting them into an ice bath,” Kyrgios said.

Kyrgios fights way into last 16

The prospect of another meeting between Kyrgios and Nadal has been a tantalising one since the Australian Open draw was made nine days ago.

Kyrgios has previously described Nadal as “super salty”, while Nadal has been visibly irritated by the Australian’s erratic on-court behaviour in the past.

To add further spice to a highly-anticipated blockbuster, Kyrgios cheekily mocked Nadal’s superstitious service routine in his second-round win over France’s Gilles Simon.

And, after Nadal thrashed Carreno Busta in his “best match of the tournament”, Kyrgios ensured it would happen by seeing off 16th seed Khachanov.

“Whatever happens between us, he [Nadal] is an amazing player. Arguably the greatest of all time,” Kyrgios said.

“At the end of the day, we’re two different tennis players. We go about it completely different.”

After clinching victory over Khachanov, Kyrgios fell to the court in celebration and laid out on the baseline before rising to wearily take the acclaim of the crowd.

Few would have predicted the drama which followed after Kyrgios, with his generally more relaxed demeanour, bettered Khachanov in all the key areas during the first two sets.

Kyrgios had a higher first-serve percentage, won more first-serve points, hit more aces and cracked more winners, while throwing in several drop-shots to unsettle the Russian.

Khachanov’s frustration at being outplayed – and some calling out from the crowd during play – was laid bare when he whacked a loose ball into the court’s roof during the third set.

That anger seemed to spur him into finding a different level, clawing a set back when Kyrgios hit a wild forehand wide and then levelling after a fourth set where he made just two unforced errors.

Kyrgios led 3-0 in the deciding first-to-10 tie-break, used to settle matches that reach 6-6 in the fifth set at the Australian Open.

Roars greeted every winning point for the Australian number two, with anguished cries heard as Khachanov fought back in a gripping battle.

The pair were deadlocked at 6-6, then 7-7, before a Kyrgios forehand into the net post gave Khachanov an opportunity to serve out the match.

However, a pinpoint backhand down the line finished a tense rally, leaving Kyrgios grinning and the crowd on their feet as Khachanov missed his chance.

Khachanov then hit a backhand into the net for Kyrgios’ third match point – one hour and 54 minutes after his first – and pushed another wide to cause pandemonium in the Melbourne Arena.

Kyrgios described the match as “insane” as he struggled to speak on court afterwards.

“At 8-7 down, I had all the thoughts. I thought I was going to lose. I was thinking about everything. I was thinking about the media if I lost, everything,” he added.

Up next, the world number one

Nadal, 33, was sharp on serve as he raced into a two-set lead in his match, allowing 27th seed Carreno Busta just five return points.

Carreno Busta fared little better in the third as 2009 champion Nadal wrapped up a one-sided win over his friend, with whom he helped Spain win the Davis Cup in November in one hour and 38 minutes.

Nadal set the tone by breaking in the second game of the match, pinching Carreno Busta’s serve another four times on a sun-soaked Rod Laver Arena.

“It was my best match of the tournament without a doubt,” said Nadal, who hit 42 winners and made just seven unforced errors.

“When the conditions are warmer, the ball bounces higher and flies through the air. That helps my game.

“I did very well with my serves and started to hit some forehands down the line. That is key for me.”

Victory also continued Nadal’s dominance over his compatriots. The Majorcan left-hander has now won his past 18 matches against Spanish opposition, stretching back to a 2016 Australian Open first-round defeat by Fernando Verdasco.

Jamie Murray and Neal Skupski have been knocked out of the Australian Open men’s doubles, losing a final-set tie-break to American pairing Sam Querrey and Steve Johnson.

The British 14th seeds saved six match points but eventually lost 4-6 7-6 (7-5) 7-6 (14-12) in the second round.

There was better news for Neal’s brother Ken who teamed up with Mexican partner Santiago Gonzalez to beat second seeds Marcelo Melo and Lukasz Kubot 7-5 7-6 (7-4) and reach the third round.

Another Briton to go through was Joe Salisbury who won alongside American Rajeev Ram. The 11th seeds defeated Tennys Sandgren and Jackson Withrow 6-3 6-3.

• Nadal cruises past Carreno Busta
• Second seed Pliskova knocked out
• Monfils beats Gulbis to reach last 16
• Where does Melbourne exit leave Williams’ chase for another Grand Slam?

Angelique Kerber was made to fight by Camila Giorgi but managed to get past the Italian in three sets and reach the Australian Open fourth round.

Germany’s Kerber, the 2016 champion in Melbourne, won 6-2 6-7 (4-7) 6-3.

It was a battle between Giorgi’s aggression and Kerber’s defence with the Italian’s 65 unforced errors key as the 17th seed went through in two hours and eight minutes.

Kerber will face Karolina Pliskova or Anastasia Pavlyuchenkova next.

• Where does Melbourne exit leave Williams’ chase for another Grand Slam?
• Gauff shines before getting on with homework, Federer through and Williams exits on epic day five
• Live scores, schedule and results
• Alerts: Get tennis news sent to your phone

Kiki Bertens, the Dutch world number 10, is the latest WTA Tour star to feature in a BBC Sport column. In her third piece at the Australian Open, the 2016 French Open semi-finalist talks about matching her best run in Melbourne, her sadness at hearing Dutch wheelchair legend Esther Vergeer is fighting cancer and whether there should be a punishment for ‘unnecessary’ medical time-outs.

If you didn’t see my second-round match in the Australian Open then that’s a good thing – it was not a great one from my perspective!

The most important thing was that I won and I still managed to do that in two sets against Australian wildcard Arina Rodionova, despite not being at my best.

That win puts me into the third round in Melbourne for only the second time in my career so I’m very happy about that.

Now I will play Kazakhstan’s world number 73 Zarina Diyas on Saturday for a place in the fourth round. Reaching the last 16 would be my best ever run here.

I’ve played Zarina once before when she beat me in Tokyo four years ago – that’s quite a long time ago in tennis terms.

I think I’m a different player now, as I’ve explained in my previous columns, but she is playing really flat so that makes it tricky.

Against Rodionova, I wasn’t at my best because my legs weren’t moving that great.

That had nothing to do with the Achilles injury which forced me to pull out of Adelaide last week and which I am continuing to manage.

My side-to-side movement was really good and I got a lot of balls back in the court. It was more like when I had opportunities to come forward I wasn’t really going through the ball with my legs.

So I stopped doing that and I was just trying to make as many balls as I could and let her finish it.

The injury did not bother me at all, but my team and I are still trying to find a balance so it does not become a bigger problem. That’s why I decided not to play doubles here.

Sometimes I like to play doubles to get some matches in, I know the more matches I play the better the level of my tennis is going to be.

But at the moment my recovery is helped by the day off between matches, meaning I can rest and have just a light practice to be ready again for the next match.

I played alongside Australian world number one Ash Barty in Brisbane earlier this month and I loved playing with her, especially in her home town.

It would have been an amazing experience to play with Ash here, but it was the best decision physically not to play in the doubles.

Players need to consider if they really need medical timeouts

Earlier this week the issue of tactical medical timeouts was raised again when Caroline Wozniacki questioned why Dayana Yastremska used one at a crucial point towards the end of their second-round match.

Obviously taking a medical timeout is allowed at any stage of the match and you can do what you want to do.

I don’t exactly know what happened in this situation and maybe it was a genuine injury.

I would like to see a rule change – or at least a discussion around the issue – where you can have an injury timeout but then you lose a point.

I think it needs something to make players consider if they really need the timeout.

I was sad to hear Dutch legend Vergeer’s cancer diagnosis

Earlier this week I read the terrible news that Dutch wheelchair tennis legend Esther Vergeer has been diagnosed with breast cancer.

Esther won an incredible 470 successive matches between 2003 and her retirement in 2013; that is why she is one of the biggest names in sport back home.

It is always really sad when you read something like that but it was good to hear her say she is full of positive energy.

I have met her on a few occasions and we know each other to say hello.

She is a huge star in the Netherlands and what she did for the sport in our country is unbelievable.

Diede de Groot is now the women’s number one wheelchair player in the world and I think that is partly because Esther made the sport so big and inspired so many good players.

Esther is loved back home and means a lot to the people. She has done a lot for sport in the Netherlands and now she is chef de mission this year for the Paralympics in Tokyo so she is still really involved.

I wish her all the best in her fight and hope she returns to full health soon.

No time for an escape room, but I have been to the casino

Melbourne is a great city and one of the favourites place on tour for many players.

I’ve been playing and practising a lot – which is a good thing, of course – so I haven’t done much yet around the city, other than a few dinners.

On Wednesday night we had a special dinner; actually, it was the birthday of my coach Elise Tamaela.

We went to Nobu – which is a favourite for the players – and that was a really nice celebration.

We got Elise a cake and it was brought to the table so we could sing ‘Happy Birthday’ to her. She was really happy with that… not!

Also I went to the casino one night with my team, although I don’t play too much.

I just like to walk around and look at what is happening. It means we don’t lose too much money!

I like to play a little bit of blackjack and a little bit of roulette but I’m not a big gambler.

One thing I really love doing is an escape room. We did that before I arrived here in Melbourne and we are definitely planning to do one here when we get the time.

But hopefully not too soon because that will mean I’m still winning!

Kiki Bertens was speaking to BBC Sport’s Jonathan Jurejko at Melbourne Park.