There is unpredictable, and then there is Nick Kyrgios.

The enigmatic 21-year-old Australian is a master of the mysterious when hitting second serves, keeping opponents off balance with his massive range of speed and spin. Sometimes it’s an 83 mph kicking mule that deceptively comes at you slow, but then leaps off the court up over your head. Other times it’s a 129 mph fastball that whizzes right by you for an ace. It’s unreadable, often unhittable and unrelenting in the clutch.

Kyrgios takes the standard guidelines for hitting second serves on board, and then proceeds to throw them out the window. He is not the first player to have such a prolific mix of second-serve deliveries, but he is certainly one of the best at executing it on the biggest stages in the most important moments.

The ATP Stats LEADERBOARDS, powered by the Infosys Information Platform, identifies that Kyrgios has the third best Serve Rating on the ATP World Tour during the past 52 weeks against Top 10 opponents, with a 288.7 rating. The 6’4″ (193cm) Aussie is sixth best on tour in the past 52 weeks against all opponents with second-serve points won, at 55.4 per cent. The mix is the primary reason. He gives you the kitchen sink with his second serve.

Kyrgios recently scored back-to-back wins against World No. 2 Novak Djokovic at the Abierto Mexicano Telcel in Acalpulco and at the BNP Paribas Open in Indian Wells. Kyrgios’ second serve was simply spectacular.

He won an impressive 62 per cent (29/47) of his second-serve points combined in both matches against one of the best returners in the game. Kyrgios’ serve was not broken in either match, and he faced only one break point in 23 service games.

Second-Serve Points Won Against Novak Djokovic

• Acapulco 75% (15/20)

• Indian Wells 52% (14/27)

In their Indian Wells round of 16 clash, Kyrgios had a substantial 46 mph difference between his slowest second serve and his fastest. To make things even more mind blowing, the two extremes happened one after the other late in the second set, helping him seal the match.

With Kyrgios serving at 5-6, 40/30 in the second set, he hit an 83 mph change-up out wide in the ad court that Djokovic barely made contact with above his head with his reaching backhand return.

Kyrgios’ next second serve came at 3/2 in the tie-break – a blistering 126 mph ace right down the middle. Djokovic split-step to cover that direction, but the slicing, snarling delivery was still well outside his reach.

Djokovic’s first-serve average speed for the match was 115 mph. Kyrgios hit 11 second serves that were faster than that. Djokovic’s fastest first serve was 128 mph. Kyrgios hit one second serve faster – a 129 mph bomb down the middle of the ad court at 1-2, 40/0 in the second set.

Kyrgios’ second serve did yield four double faults, but it also notched up three of his 14 aces. Kyrgios was lights out in this area during their Acapulco match, hitting 25 aces, while yielding just one double fault.

Kyrgios is not simply bending the traditional second-serve rules of our game. He is breaking them in half.

#NextGenATP star Alexander Zverev knocked out top seed Stan Wawrinka on Tuesday at the Miami Open presented by Itau to advance to his first ATP World Tour Masters 1000 quarter-final. The 19-year-old Zverev came back from a set down and ran away with the fourth-round contest, winning 12 of the final 15 games to claim victory 4-6, 6-2, 6-1 in one hour and 44 minutes.

“I had to be aggressive. I felt like he was the one controlling all the points all the time, so I had to change that. It worked out well for me. Happy to be in the quarter-finals now. Hopefully I can play as great as I did today,” Zverev said.

The German was nearly untouchable on his serve. He saved four of five break points and won almost 75 per cent of his service points, including 68 per cent of his second-serve offerings. Zverev also broke Wawrinka five times – all in the last two sets.

 Watch Full Match Replays

He improves to 2-0 against Wawrinka in their FedEx ATP Head2Head rivalry. Zverev won their first contest last September for his maiden title at the St. Petersburg Open. “Both times I played him I played [with] very high confidence and I played very well,” Zverev said. “I think we both have one of the best backhands on tour, both of us, so that maybe helps me a little bit. He likes to use that corner a lot on the opponent.”

For a berth in his first Masters 1000 semi-final, Zverev will face Aussie Nick Kyrgios, who hit 12 aces to beat Belgian David Goffin 7-6(5), 6-3 in one hour and 37 minutes. Kyrgios improves to 2-0 against Goffin in their FedEx ATP Head2Head series, having also beaten the right-hander in the Tokyo final last year.

The 21-year-old Kyrgios saved both break points faced and broke the 26-year-old right-hander once. Goffin, serving at 1-2 in the second set, had erased four break points in the game but netted a forehand on the fifth break chance to give Kyrgios a 3-1 lead. The game lasted 26 points and more than 13 minutes.

Kyrgios’ quarter-final against Zverev will be a rematch of their third-round contest at the BNP Paribas Open earlier this month. Kyrgios took that FedEx ATP Head2Head meeting, their first, 6-3, 6-4.

The opportunity marks quite the turnaround for Zverev, who was inches away from losing on Monday and heading home. The 6’6″ right-hander had to save three match points against American John Isner to escape to the fourth round. “I had to use the opportunity. I knew I got a second chance in this tournament, so I’m really happy that I used it,” Zverev said.

Wawrinka had been in top form before their fourth-round showdown. The Swiss right-hander hadn’t dropped a set in South Florida and was coming off his maiden final run at the BNP Paribas Open last week. “One bad game to start the second set and then it was tough for me,” Wawrinka said. “I completely went down physically and mentally, and also my tennis was completely out. I had no more gas.”

Roger Federer stayed perfect at the Miami Open presented by Itau on Tuesday, persevering through a back-and-forth and gritty fourth-round contest against Roberto Bautista Agut 7-6(5), 7-6(4). The Swiss right-hander needed nearly two hours to improve to 6-0 against the Spaniard in their FedEx ATP Head2Head series, and afterward likened his recovery to going clubbing.

“I think coming out of a brutal match and then feeling fit like a fiddle in the morning, it’s like when you go clubbing,” said the 35-year-old Federer. “Same thing. You know, you don’t feel the same when you’re older. (Laughter.) It’s a good example because everybody knows that feeling. Not that I’ve ever — you know?”

Federer reaches his second consecutive ATP World Tour Masters 1000 quarter-final, where he’ll face 10th seed Tomas Berdych, who dismissed Frenchman Adrian Mannarino 6-3, 7-5 on Tuesday afternoon. Federer leads their FedEx ATP Head2Head series 17-6, including a straight-sets win earlier this year at the Australian Open.

 Watch Full Match Replays

Nothing came easy for Federer on Tuesday, though. The Swiss was made to labour throughout his sixth meeting with Bautista Agut, who saved eight of 10 break points and broke Federer once during their Round of 16 battle. Federer has now been broken only twice during his three Miami matches.

“I felt good overall. It was a different kind of match,” said Federer. “It wasn’t the big-serving match where you’re only going to see so many looks, so when you miss chances you always feel a bit frustrated sometimes. That’s where you got to keep a positive mindset and make the right plays.

“I thought Roberto did a good job of making shots, staying offensive when he could, fending off a lot of good shots that I hit. Then it was tough. The sun was coming from the side in the beginning so it’s hard to chase the lines. At the end I’m very happy and pleased that I got it done in straight sets.”

The World No. 6 sought to be aggressive from the get-go against Bautista Agut, attacking the net often and trying to jolt the 14th seed out of his comfort zone. Federer started by breezing through his service games, especially dominating with his first serve. The fourth seed would win 89 per cent of his first-serve points for the match.

But Federer struggled to land his first serve at 4-4, and Bautista Agut took advantage. Seeing another second serve, the 28 year old stepped into a backhand up the line and broke for a chance to serve out the set. Nerves would get the best of the Spaniard during the 10th game, though, as Federer broke to love when Bautista Agut double faulted.

Federer struck a forehand pass to escape in the first-set tie-break. To start the second set, it looked as if Federer would start to pull away. He broke in the opening game but Bautista Agut broke right back, and to a second tie-break they headed, where Federer solidified his dominance in their FedEx ATP Head2Head series, having won all 14 sets they’ve played, dating back to the 2014 US Open.

Second seed Kei Nishikori survived a stern challenge from Federico Delbonis on Tuesday, advancing to the fourth round of the Miami Open presented by Itaú with a 6-3, 4-6, 6-3 victory over the Argentine.

After snatching the second set to level the match, the No. 57-ranked Delbonis, who had upset 15th seed Pablo Carreno Busta in the second round, took an early break lead in the decider. But Nishikori reeled off five of the last six games to prevail in two hours and 14 minutes.

The 27-year-old Nishikori is looking to win his first ATP World Tour Masters 1000 crown and goes on to face Fabio Fognini for a spot in the last four.

“I tried to stay calm and focus again,” said Nishikori, reacting to the loss of the second set. “I knew I [still] hde a lot of chances after losing the set. Even though I was down a break, 2-1 [in the third], I was focusing well. I knew if I fight through I will have some chance, so I just tried to concentrate one game at a time.

“I hope I can win some big tournaments sometime soon. I think that’s my biggest next goal.”

 Watch Full Match Replays

Fognini had a much smoother route through the fourth round, dismissing American Donald Young 6-0, 6-4 in 66 minutes. The Italian will look to overturn a 0-2 FedEx ATP Head2Head record against Nishikori, who was runner-up in Miami last year (l. to Djokovic).

In an all-American match-up, Jack Sock won 71 per cent of his service points as he defeated #NextGenATP Jared Donaldson 6-2, 6-1 in 63 minutes.

Sock is coming off his first ATP World Tour Masters 1000 semi-final showing in Indian Wells, where his run was ended by Roger Federer. The 24 year old has made early moves in the Emirates ATP Race To London, currently ninth after a career-best start to the year, which has seen him win two ATP World Tour titles in Auckland and Delray Beach.

“The more matches you win, the better you feel, the more confident you are,” Sock said. “Physically, mentally [I’ve] never felt better or stronger, so [I’m] just excited for the rest of the year.”

View FedEx ATP Head2Head for the following match-ups & vote for the players you think will win!
Wawrinka vs Zverev  |  Federer vs Bautista Agut  |  Nadal vs Mahut  |  Nishikori vs Delbonis

View Round of 16 schedule

• DAY 7 PREVIEW: Tuesday at the Miami Open, presented by Itau, features all eight fourth-round matches, including four of the top five seeds: No. 1 Stan Wawrinka, No. 2 Kei Nishikori, No. 4 Roger Federer, and No. 5 Rafael Nadal. The field also features three Americans (No. 13 Jack Sock, Donald Young, and qualifier Jared Donaldson), the most since 2004, when there were four (Roddick-Won, Spadea-SF, Agassi-4R, Martin-4R). Six players are looking to reach their first ATP Masters 1000 quarter-final: No. 16 Alexander Zverev, Federico Delbonis, Nicolas Mahut, Adrian Mannarino, along with Donaldson and Young. Zverev, at 19, is the youngest player in the field, while Federer, at 35, is the oldest. There are 11 countries represented in the 4R, led by the U.S. (3), France (2), Spain (2) and Switzerland (2). One Each: Argentina, Australia, Belgium, Czech Republic, Germany, Italy, and Japan.

Opening the day’s action on Stadium, Nishikori faces Delbonis, who upset No. 15 Carreno Busta in the second round. Delbonis is one of five unseeded players (compared to only three seeds) remaining in the bottom half of the draw, while in the top half, only one unseeded competitor has made it this far. Nishikori, a finalist in Miami last year (l. to Djokovic), won the only previous meeting between the two, a 2011 qualifying-round encounter in Rome.

Next up on the men’s Stadium slate, Nadal plays Mahut for the first time since 2011. Nadal played his 1,000th career match on Sunday, overcoming a 0-6 score in the first set to defeat Kohlschreiber in three. Mahut defeated Pella in straight sets on Sunday, and upset No. 23 Johnson in the second round. The career head-to-head is knotted at one apiece; Nadal won the last encounter via retirement at the 2011 US Open.

Rounding out the Stadium court day session, Federer goes toe-to-toe with No. 14 Roberto Bautista Agut. The Swiss star has never lost a set against the Spainard, claiming all 12 sets in their previous five encounters. Like this one, four of their past matches have taken place in the round of 16. Federer service games will be a clash of titans: Fed has been broken only once in two matches here, while Bautista Agut leads the field in rate of return games won, having broken his opponents in 11 of 23 tries.

The evening session concludes with both of last year’s losing semi-finalists, No. 12 Nick Kyrgios and No. 8 David Goffin. Their only previous match was last year’s Tokyo final, in which Kyrgios triumphed in three sets. Both men needed three sets yesterday as well, with Kyrgios edging Karlovic in a deciding-set tiebreak, and Goffin coming back to overcome Schwartzman.

The first two matches on Grandstand feature the American hopes, beginning with an unseeded clash between Young and Fabio Fognini, who has lost to the American in both previous meetings. In his third-round defeat of Paire, Young improved to a tour-best 10-1 in tiebreaks this season, and if he reaches the quarterfinal, it will be the first time since 2008 that two Americans reached the final eight (Roddick, Blake). After that is the all-American fourth-rounder between Sock and Donaldson, the first encounter between the two. Sock is tied with four other players (including Goffin) with 17 wins on the season, while Donaldson is trying to become the first qualifier since Canas (2007, l. to Djokovic) to reach the quarterfinals.

The second half of the Grandstand slate begins with No. 10 Tomas Berdych—making his fifth consecutive appearance in the Miami fourth round, and 9th in 10 years—against Mannarino, in his second round-of-16 showing (2015, l. to Thiem). Berdych has won all three matches between the two, and is one of only four players remaing (w/ Federer, Wawrinka, Sock) who have yet to drop a set. Last up is top seed Wawrinka against Zverev, who needed to save match point and fight through three tiebreaks to oust Isner last night. Wawrinka is celebrating his 32nd birthday, an anniversary he hopes to mark by reaching his first-ever Miami quarter-final. He and Zverev have played once before, in last year’s St. Petersburg final, where Zverev came out on top to win his first-ever ATP World Tour title.