Novak Djokovic moved a step closer to retaining the Australian Open title with a straight-set semi-final win over injury-hit rival Roger Federer.

Serbia’s Djokovic was 4-1 and 40-0 down in the opening set before recovering to win the tie-break.

That laid the platform for the 32-year-old second seed to go on and win 7-6 (7-1) 6-4 6-3.

Djokovic, aiming for a 17th Grand Slam title, will face Dominic Thiem or Alexander Zverev in Sunday’s final.

“The match could have definitely gone a different way if he had used those break points [in the sixth game],” Djokovic said.

“He started well – I was nervous.

“Respect to Roger for coming out tonight. He was obviously hurt and wasn’t close to his best in terms of movement.”

Victory would mean a record-extending eighth Australian Open triumph for Djokovic, who has lost just three matches at Melbourne Park in the past 10 tournaments.

It would also move him within three of 38-year-old’s Federer’s all-time record of 20 men’s Grand Slam singles titles and within two of Spain’s Rafael Nadal, who lost to Thiem in Wednesday’s quarter-final.

• Reaction: Djokovic v Federer live coverage
• Muguruza beats Halep to reach final
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Ruthless Djokovic proves too strong

Djokovic was the heavy favourite to beat his long-time rival in what was their 50th meeting.

Questions were raised about Federer’s fitness going into the match, having struggled with a groin problem in his epic quarter-final against Tennys Sandgren.

And he needed an off-court medical timeout, presumably for the same problem, at the end of the first set.

Djokovic turned into his ruthless best in the second set after a tight opener, giving away little on his serve and applying serious pressure on his opponent’s.

After Federer survived break points in the second and sixth games, Djokovic took his first chance in the 10th, scampering to pick up a drop-shot and scoop away sharply cross-court.

That silenced many in the 15,000 crowd on Rod Laver Arena who were supporting Federer.

But not the noisy bunch of Serbs sat behind his player box, to where he shot a steely side-glance as he clenched a fist in celebration.

From that point it was difficult to envisage a comeback for Federer, who somehow came through five-set matches against third-round opponent John Millman and then Sandgren.

Djokovic picked his moment to break in the third set, finishing off a precise point with a wonderful forehand winner that kissed the sideline for a 4-2 lead.

Federer said after beating Sandgren he would always believe in miracles until defeat was confirmed.

This time it would truly have been a miraculous escape against someone of Djokovic’s class.

Federer valiantly levelled at 30-30 as Djokovic tried to serve out the match, only for the Serb to refocus and seal victory in two hours 18 minutes.

Federer starts well but momentum swings

Concerns had been voiced by some at Melbourne Park that Federer might pull out in the hours leading up to the match. They proved unfounded.

Instead he came out firing in an extraordinary start in which his fitness issues did not stop him building up a lead.

Although he had to stave off two break points in the opening game, he eventually came through a six-minute hold before the pair exchanged three successive breaks.

Federer turned the set 4-1 in his favour with supreme serving and shot-making, leaving the stunned crowd murmuring in excitement at what they had just seen.

“It was not exactly the right mindset for me at the start – I was looking at how he was moving rather than executing my shots,” Djokovic said.

Djokovic faced three more break points to go 5-1 down but hung on to leave Federer still needing two more games.

A 61-second hold to love – ace, backhand-volley winner, ace, service winner – put him within one.

Then, as the aces and winners started to dry up, momentum swung back as Djokovic won the next three games as a tie-break beckoned.

The pair had won 44 points each going into the set decider, despite Federer hitting 25 winners to Djokovic’s six.

But Djokovic upped the ante in the breaker, blasting an ace past Federer for a 5-1 lead at the changeover and two more winners seeing him through.

That proved pivotal in the context of the match and ultimately terminal to Federer’s chances.

“I managed to dig my way through and it was very important to win that first set,” Djokovic said. “Then mentally I could relax and swing through the ball a bit more.”

Race to be the ‘GOAT’ continues

Djokovic’s victory over Federer in last year’s historic Wimbledon final took him closer to the Swiss’ Grand Slam tally than he has ever been.

Now the Serb, who has won six of the past nine tournaments in Melbourne, is aiming to further reduce the gap on Sunday.

Almost six years younger than Federer, Djokovic could add plenty more, barring a loss of form or fitness.

His pursuit of Federer and Nadal is made more remarkable by the fact he won his first major in 2008 – when Federer had claimed 13 and Nadal five – and only added a second three years later.

Nadal, however, is another major obstacle for Djokovic – and also a concern for Federer.

Sofia Kenin reached her first Grand Slam final by beating a nervous top seed Ashleigh Barty in straight sets in the Australian Open semi-finals.

The 21-year-old American, seeded 14th, won 7-6 (8-6) 7-5 in sweltering conditions at Melbourne Park.

Australian Barty, aiming to become the first home woman to reach the final in 40 years, failed to convert two set points in each set.

Kenin will face unseeded Spaniard Garbine Muguruza in Saturday’s final.

The two-time Grand Slam champion saw off fourth seed Simona Halep 7-6 (10-8) 7-5.

• Muguruza beats Halep to make final
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Florida-raised Kenin, who was born in Russia before moving to the United States as a baby, dropped her racquet on the floor and cupped her face with both hands when Barty hit a return long on match point.

“I’m speechless. I can’t believe it. I’ve dreamed of this since I was five years old. I’ve worked so hard to get here,” she said.

Kenin is the first American to reach the Australian Open final, outside of the Williams sisters, since Lindsay Davenport in 2005.

She was a child prodigy in the States, having made numerous television appearances and played alongside the big names when she was young.

Now she has fulfilled that promise by reaching her first Grand Slam final.

Possessing a feisty nature and a tremendous will-to-win, she showed all of her qualities to overcome Barty and shock the expectant crowd on Rod Laver Arena.

Australia’s wait continues

Barty insisted she was not being swept away by growing public excitement as she aimed to follow Wendy Turnbull in 1980 by reaching the Melbourne final, and ultimately become the nation’s first champion here – either male or female – since Chris O’Neil in 1978.

Yet she looked edgy in the crucial moments throughout the match.

Barty’s service game – where she won 20 of her 24 service points before coming under pressure for the first time at 5-5 – kept her out of serious trouble.

That was until the first-set tie-break when tightness crept in again, missing two set points, before Kenin cracked two winners in a row to swing momentum back in her favour.

With a set point on serve, the American took it when Barty swung at a second serve and lumped the ball into the net.

Barty started to play more freely in the second, breaking early for a 2-1 lead, and finally started to cause problems for Kenin with her backhand slice.

But she got tight again in the crucial moments, unable to take two more set points when serving for the second at 5-4.

Anguished cries from the passionate home support greeted a drive forehand volley into the net on the second.

From that point she struggled to recover.

Barty did save the first match point with a whipping cross-court forehand winner that ended a 17-shot rally but succumbed to the second as Kenin won in one hour and 45 minutes.

Barty, who won her maiden Grand Slam at the French Open in June, acknowledged playing in her first Australian Open semi-final was a “different experience”.

However, the 23-year-old did not think she was adversely affected by the occasion.

“I put myself in a position to win the match and just didn’t play the biggest points well enough to be able to win,” said Barty, who appeared at her post-match news conference with 12-week-old niece Olivia on her lap.

“I have to give credit where credit’s due. Sofia came out and played aggressively on those points and deserved to win.”

• Live scores, schedule and results
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Extreme heat arrives in Melbourne

Melbourne is known for its variable weather and, after poor air quality caused by the devastating bushfires, and torrential rain earlier in the tournament, it was the turn of scorching heat to potentially cause problems.

Temperatures touched 40C for the first time during the fortnight, meaning the Australian Open’s extreme heat policy came into force.

Their scale reached 4.0 just before the players came on court, triggering an extended break between the second and third sets – if it had gone that far.

Both players are well accustomed to playing in sweaty conditions, Barty hailing from Queensland and Kenin growing up in Florida.

Neither looked adversely affected by the temperatures and humidity, although sensibly used ice towels at the changeovers.

The heat scale rocketed up to 4.9 during the match, just falling short of the 5.0 required to stop the match and close the court’s roof.

Play was suspended on the outside courts in the wheelchair and junior competitions where the threshold for stopping play is lower.

Rows of empty seats in the sun-soaked parts of Laver started to appear as the match wore on, while fans outside opted to watch the big screen from shaded areas under trees rather than the available deckchairs.

Garbine Muguruza continued her recent revival by reaching the Australian Open final with a straight-set win over Romania’s Simona Halep.

The unseeded Spaniard, 26, battled past the fourth seed in a tense 7-6 (10-8) 7-5 semi-final victory.

The two-time Grand Slam champion fought off four set points in the opener and twice came back from a break down in the second.

She will face American Sofia Kenin in Saturday’s final.

It is Muguruza’s first appearance in a Grand Slam final since she won the Wimbledon title in 2017.

More to follow.

• Kenin beats top seed Barty to make final
• Live scores, schedule and results
• Alerts: Get tennis news sent to your phone

Alexander Zverev is through to a Grand Slam semi-final for the first time after defeating Stan Wawrinka in four sets at the Australian Open.

The German seventh seed beat the Swiss three-time Grand Slam champion 1-6 6-3 6-4 6-2, dropping a set for the first time in Melbourne this year.

He lost the first five games in only 16 minutes but bounced back to convert five out of 13 break points.

The 22-year-old will face fifth seed Dominic Thiem in the last four.

Austrian Thiem beat world number one Nadal 7-6 (7-3) 7-6 (7-4) 4-6 7-6 (8-6) in the Rod Laver Arena night session.

In the other semi-final, 20-time Grand Slam champion Roger Federer will face last year’s Australian Open winner Novak Djokovic on Thursday.

• Halep to face Muguruza in semi-finals
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• Britain’s Whiley out of wheelchair singles
• Live scores, schedule and results

Wawrinka, who won the Australian Open in 2014, has now been knocked out at the quarter-final stage in three of the past four Grand Slams.

The 34-year-old started strongly against Zverev, racing through the opening set and winning 16 out of 19 points on his serve, even though his first-serve percentage was only 32%.

But Zverev really stepped up in the second, not dropping a point in five service games and breaking once to level at one set all.

Both players lost their opening service games at the start of the third, before Zverev moved 4-2 up and then served out the set.

The German opened up a 4-0 lead in the fourth as Wawrinka sprayed shots all over the court, possibly feeling the effects of two five-set matches earlier in the tournament against Andreas Seppi and Daniil Medvedev.

Zverev, who had not gone beyond the fourth round in Melbourne prior to this year, said: “I don’t know what to say. I’ve done well in other tournaments, I’ve won Masters, I’ve won the ATP Finals, but I never could break that barrier in a Grand Slam. I’m happy to be in the semi-finals.”

Addressing the crowd, he added: “You guys cannot imagine what this means to me and I hope it will be the first of many.”

Before the tournament, Zverev pledged to donate the full winner’s prize fund to the Australian bushfire relief appeal if he claimed the title.

When asked whether he intended to keep his promise following victory over Wawrinka, he said: “I hope I can make it happen. I made the people of Australia a promise. I will keep that promise.

“I’m not a money-driven person. My parents always taught me with money you should achieve things that help others and help the people that need the money. For me right now, four million Australian dollars would be nice, very nice – I could buy myself a few cars of something.

“But there are people who actually need it for their homes, for rebuilding wildlife, houses and the life they once knew, so it’s much more important that they get that money.”