As Novak Djokovic limped from Rod Laver Arena for treatment midway through his second-round clash against qualifier Enzo Couacaud, it was not just his mind that was spinning.
His grip on favouritism for the Australian Open was drifting by the minute as he received treatment off the court for the hamstring issue that has hindered him for a fortnight.
The nine-time champion ultimately progressed with a 6-1, 6-7 (5-7), 6-2, 6-0 victory to set up a third-round clash against three-time major semi-finalist Grigor Dimitrov.
But it is clear there is an issue. Paul McNamee noted after his opening-round win Djokovic is shortening points as a result of his hamstring and this was also evident against Couacaud.
Far from being a lock for a remarkable 10th Australian Open title, Djokovic looks vulnerable.
His remaining rivals, beginning with former ATP Tour Finals champion Dimitrov on Saturday night on Rod Laver Arena, will be well aware of his injury issues and planning accordingly.
But beware the wounded Serbian. History shows it is foolhardy to write off the champion.
Djokovic won an Australian Open two years ago despite suffering from a tear of 1.7 centimetres in his abdominal muscle in the third round. That tear had extended to 2.5cm by the time of his victory over Daniil Medvedev in the decider.
He is hindered physically but retains a mental mastery over most, and it is clear he is determined to conquer Melbourne once again after the drama he went through in 2022.
What is clear is that if Djokovic is fit enough to reach the final, where he could face stars including Medvedev and Stefanos Tsitsipas, he will be the heavy favourite.
In nine Australian Open finals appearances, he is unbeaten. But plotting a path through these competitors, while hoping his hamstring holds, is the key to his chances.
HEAD-TO-HEAD
Round 3 rival
Grigor Dimitrov
Age: 31
Country: Bulgaria
Ranking: 28
Seeding: 27
Head to head: 9-1 (Djokovic)
In most eras, it is conceivable Dimitrov would have compiled a career placing him among the greats of the game. But he was born in the era of “The Big Three” of Djokovic, Rafael Nadal and Roger Federer. Ranked as high as No.3, Dimitrov reached semi-finals at Wimbledon in 2014, the Australian Open in 2017, and the US Open in 2019. He was the champion at the ATP Tour Finals in 2017 and has beaten Djokovic once, admittedly on clay in the Monte Carlo Masters nearly a decade ago. He is a legitimate threat.
Possible round 4 opponents
Alex de Minaur
Age: 23
Country: Australia
Ranking: 24
Seeding: 22
Head to head: 0-0
De Minaur was overshadowed in the lead-in to this Australian Open by the focus on Nick Kyrgios, but his preparation was superb and his form is outstanding. He defeated Nadal in the United Cup and Dominic Thiem in an exhibition at Kooyong, where he was later edged by a resurgent Andy Murray. A good winner over crafty Frenchman Adrian Mannarino in the second round, the 2020 US Open quarter-finalist has the drive and desire to test the best.
Benjamin Bonzi
Age: 26
Country: France
Ranking: 48
Seeding: N/A
Head to head: 0-0
Bonzi identified himself as a player to watch in 2021 when claiming six ATP Challenger Tour titles and has continued to progress up the rankings since then. He reached the third round of a grand slam for the first time when defeating tough Spaniard Pablo Carreno Busta in a deciding tie-breaker. He shapes as a knockout hope.
Possible quarter-final opponents
Holger Rune
Age: 19
Country: Denmark
Ranking: 10
Seeding: 9
Head to head: 1-1
Rune is both a star of the future and a present threat, as he established when defeating Djokovic in the final of the Paris Masters in early November. The Danish teenager reached the quarter-finals of the French Open earlier in 2022 and also defeated Tsitsipas in October to win the Stockholm Open. Rune is a quality competitor and an outstanding striker of the ball who is a significant threat.
Ugo Humbert
Age: 24
Country: France
Ranking: 106
Seeding: N/A
Head to head: 1-0 (Djokovic)
Humbert is a talented left-hander who is a superior player to the ranking currently against his name. Consistency has been an issue, but he is the winner of three ATP Tour titles and has been ranked as high as No. 25. Djokovic put an end to his career-best run at a grand slam in straight sets at Wimbledon in the fourth round in 2019.
Dan Evans
Age: 32
Country: England
Ranking: 30
Seeding: 25
Head to head: 1-0 (Evans)
An athletic, tough player with a quality all-round game, Evans caused a major upset when beating Djokovic in straight sets at the Monte Carlo Masters in 2021. His best effort at grand slam level came in Melbourne in 2017 when reaching the fourth round, so he would be setting new ground here if he were to play the nine-time champion.
Andrey Rublev
Age: 25
Country: Russia
Ranking: 6
Seeding: 5
Head to head: 2-1 (Djokovic)
Rublev is a talented Russian capable of beating anyone on his day, as he demonstrated when defeating Djokovic on his home turf in a final in Serbia last year. A superb ball-striker, Rublev has won 12 ATP Tour titles but his grand slam efforts belie his talent, with the right-hander reaching six quarter-finals at major level without progressing.
Possible semi-final opponents
Alexei Popyrin
Age: 23
Country: Australia
Ranking: 113
Seeding: N/A
Head to head: 1-0 (Djokovic)
Popyrin has proven himself an ironman in this Australian Open with stunning five-set defeats of Chun-Hsin Tseng and Taylor Fritz, the latter triumph arguably a career-best. The athletic Australian tends to produce his best form in majors, particularly on the hardcourts in Melbourne and New York, which includes a win over Thiem. Djokovic was far too good for him when they met in Japan in 2019, but Popyrin is on the rise.
Ben Shelton
Age: 20
Country: United States
Ranking: 89
Seeding: N/A
Head to head: 0-0
Shelton had never left the United States before this summer, but is having a road trip to remember in Australia. The son of former professional Bryan Shelton, the left-hander turned professional in 2022 and rapidly made a mark on the tour with a string of good wins.
JJ Wolf
Age: 24
Country: United States
Ranking: 67
Seeding: N/A
Head to head: 0-0
Wolf is a hard-working American who has only played three grand slam tournaments, but reached the third round on each occasion. His all-round game is well-suited to hard courts. Nick Kyrgios defeated him at the US Open in 2022, but Wolf is maturing as a player.
Michael Mmoh
Age: 25
Country: United States
Ranking: 107
Seeding: N/A
Head to head: 0-0
Luck proved a fortune for Mmoh, who only moved into the Australian Open main draw as a lucky loser after falling to Sydney’s Aleksandar Vukic in qualifying. He had his plane ticket home booked and was on the way out before withdrawals opened a spot, and he has made the most of this to post a career-best performance at a grand slam.
Andy Murray
Age: 35
Country: Scotland
Ranking: 66
Seeding: N/A
Head to head: 25-11 (Djokovic)
Should a semi-final eventuate between Murray and Djokovic, it will be a reprisal of one of the great rivalries in tennis between champions born a week apart. A three-time major winner, Murray has been a true braveheart to date in Melbourne when throwing back the clock. Djokovic denied the Scot in Australian Open finals in 2011, 2013, 2015 and 2016, as well as a classic semi-final in 2012.
Roberto Bautista Agut
Age: 34
Country: Spain
Ranking: 25
Seeding: 24
Head to head: 9-3
Bautista Agut has compiled an excellent record in professional tennis and, in a rarity for Spaniards, saved his best form for hardcourts and grass. The only seeded player to survive to the third round in his quarter of the draw, the 2019 Wimbledon semi-finalist shapes a significant hurdle to Murray. His three wins over Djokovic have been on hardcourts, so if both are to survive to the semi-finals, the 11-time ATP Tour titleist would fancy his chances.
Tommy Paul
Age: 25
Country: United States
Ranking: 35
Seeding: N/A
Head to head: 0-0
Paul is a classy competitor who only narrowly missed an Australian Open seeding. A boy’s finalist at the 2015 French and US Opens, Paul won the Stockholm Open in 2021 and has developed well in senior ranks. He made a career-best run to the fourth round at Wimbledon last year and is more than capable of delivering strong grand slam performances.
Jenson Brooksby
Age: 22
Country: United States
Ranking: 39
Seeding: N/A
Head to head: 1-0 (Djokovic)
A major shock looked on the cards when Brooksby ripped through the opening set of his only encounter against Djokovic at the US Open in 2021. While the 21-time major winner found his rhythm against the slightly unconventional baseliner from Sacramento, it indicated Brooksby had the talent and temperament to succeed at grand slam level.