Novak Djokovic was given a scare by Croatian teenager Dino Prizmic in the longest first-round match of his grand slam career.
The world number one is a big favourite to win an 11th title at Melbourne Park, where he has not lost since 2018, but he dropped the second set as 18-year-old Prizmic showed what makes him a major talent for the future.
The qualifier was briefly a break up in the third set and kept battling after Djokovic stepped things up before the defending champion finally clinched a 6-2 6-7 (5) 6-3 6-4 victory on his seventh match point after four hours and one minute.
The signs did not look good for Prizmic when he dropped his opening service game and then took a medical time-out at 2-3 for treatment to his left groin.
He already had tape on his right arm and could find nothing to hurt Djokovic in the first set, but things began to change early in the second.
Djokovic won a staggering 17 of his 19 tie-breaks at grand slams in 2023, including 15 in a row from the second round in Melbourne to the Wimbledon final, but here he played a very poor one and suddenly what had seemed a straightforward occasion became anything but.
Djokovic, who was dabbing his brow and puffing his cheeks, was making a lot of uncharacteristic errors and Prizmic fought back from 2-0 down in the third set to lead by a break at 3-2.
There was concern on the face Djokovic’s coach Goran Ivanisevic, who was among the spectators watching his countryman Prizmic’s run to the French Open junior title last year.
Djokovic ultimately found a way through, but the 36-year-old’s rivals will have been watching closely.
Fifth seed Andrey Rublev was hugely relieved after edging past Brazil’s Thiago Seyboth Wild in a fifth-set tie-break.
Rublev had in his mind his good friend Daniil Medvedev’s exit to Seyboth Wild at the same stage of the French Open last summer and he trailed 4-1 in the deciding tie-break after seeing a two-set lead and then four match points come and go.
But Rublev fought his way back to clinch a 7-5 6-4 3-6 4-6 7-6 (10/6) victory after three hours and 42 minutes.
Former Wimbledon finalist Matteo Berrettini was a casualty without taking to the court, the Italian pulling out as his injury woes continued.
Berrettini had been due to face Stefanos Tsitsipas on Rod Laver Arena on Monday in one of the plum ties of the first round.
But on Sunday afternoon tournament organisers announced he had withdrawn with a right foot injury, making it the fourth time in the last eight grand slam tournaments where he has not been able to play a match.
Berrettini has been replaced in the draw by Belgian lucky loser Zizou Bergs, who will take on Tsitsipas.
Fourth seed Jannik Sinner, one of the favourites for the title following his stellar end to 2023, began his campaign with a straight-sets win over Botic van de Zandschulp.
Sinner, who beat Djokovic twice in a matter of days at the ATP Finals and Davis Cup in November, was a 6-4 7-5 6-3 winner on Rod Laver Arena.
The Italian did not play a warm-up tournament after his late finish to last season and he said: “I feel like I started off actually really well for the first match.
“Then after I had some moments where I made a couple of wrong choices, but this can happen. It was important today for me because I was looking forward to stepping on the court.”
Twelfth seed Taylor Fritz was twice a set down to Facundo Diaz Acosta and needed treatment after rolling his ankle but recovered to claim a 4-6 6-3 3-6 6-2 6-4 victory.
Former finalist Marin Cilic played his first grand slam match since the US Open in 2022 following knee surgery but was beaten in four sets by Hungary’s Fabian Marozsan.
