Novak Djokovic secured his spot in the Australian Open third round after a four-set win over Enzo Couacaud – but the Serbian continues to struggle with a hamstring problem.
Djokovic took a medical timeout during the second set and looked in some pain before eventually coming through 6-1, 6-7, 6-2, 6-0 at Melbourne Park.
The dogged win set up a clash against Bulgaria's Grigor Dimitrov, who swept past another Serb, Laslo Djere, 6-3, 6-2, 6-0.
Djokovic, who also called for a drunk spectator who was heckling him to be thrown out, came into the tournament with the injury having picked it up during his run to a 92nd tour-level title at the Adelaide International this month.
The fourth seed eased through his first-round match against Roberto Carballes Baena and said afterwards that his leg was improving but during the second against the world No 191, Djokovic started to show signs he was again feeling the injury.
“To be honest, it is not good at all. I will take it day to day,” the 21-time Grand Slam winner told Eurosport.
“It was better last match, the feeling, than tonight, but that is all I can say and now it is up to God to help me and the physio and everyone. I hope I will be able to recover and be ready for a tough match next up.”
After racing through the first set, he went off for a medical timeout for treatment at 4-5 in the second, with his movement hampered. He returned to lose the tiebreak before recovering his poise.
“There was a lot happening tonight and Enzo deserves credit, he played some really great tennis, especially in the second set,” said the 35-year-old, who is looking to win a record-extending 10th Australian Open crown.
“We both had medical timeouts and struggled a little bit, but I managed to respond in the third set and especially the fourth.”
In an early setback for Couacaud, he turned his ankle when stretching for a volley as he was broken to go 3-1 down in the opening set.
Fourth seed Djokovic exploited the injury, pushing him around the court, and broke again to stroll through the set in 41 minutes with Couacaud managing just three winners.
The next set, dominated by long rallies, went with serve before Djokovic sought treatment at 4-5 after wincing on a backhand.
He returned with his thigh seemingly retaped and Couacaud forced the set to a see-sawing tiebreak where he prevailed. Djokovic found a new wind in the third set, banking an early break and never looked back rom there.
Although one fan attracted his ire in the fourth set, however, after repeatedly making noise while Djokovic was preparing to serve.
“He's drunk out of his mind, he's provoking, he's not here to watch tennis, what are you going to do about it?” he asked the umpire.
Djokovic's half of the draw opened for him earlier on Thursday when second seed Casper Ruud was knocked out, which followed Wednesday's exit of top seed Rafa Nadal.