Daniil Medvedev was troubled by the Melbourne heat but benefited from the tearful retirement of opponent Terence Atmane to move through to the second round of the Australian Open.
The third seed, twice a beaten finalist here, dropped the first set to French qualifier Atmane and called the trainer for treatment on his thighs.
But ultimately it was Atmane who decided that he could not go on, the 22-year-old calling it a day trailing 5-7 6-2 6-4 1-0 before sobbing on his chair with head in hands.
“Here I think what is tough is that the conditions were not the toughest I have ever played in but since one week we didn’t really have hot days,” said Medvedev, who next faces Finn Emil Ruusuvuori.
“So here, first match for me, he’s not used to grand slams also yet, so a lot of nerves. The heat is there. So physically it’s not easy I think. It’s tough for everyone.
“I’m happy that I managed to be stronger physically because it was not easy at one moment. At this moment he started cramping. Just have to stay in there and I’m happy to go through.”
Last year’s beaten finalist, Stefanos Tsitsipas, also found himself a set down to lucky loser Zizou Bergs before fighting back to win 5-7 6-1 6-1 6-3.
Tsitsipas, who had been due to face Matteo Berrettini before the Italian pulled out, said: “Great game of tennis the second and third sets of the match.
“I wasn’t focused too much on score and I did a great job there, coming up with powerful shots, pressing early on during the rallies. It felt great to be at that level of tennis.”
The seventh seed has been battling to recover from the back injury that saw him withdraw from the ATP Finals in November.
It has still affected him in the early stages of this season, with Tsitsipas pulling out of a charity match last week, but he is optimistic he is on the right track.
“It was a tricky part during the pre-season to be faced with something like this,” said the Greek, who has modified his service action as a result.
“But now I’m healthy. I’m headed in the right direction. I feel like I can keep adding to it and eventually see myself the way I was able to play at the beginning of last year.”
American Ben Shelton, who made a breakthrough run to the quarter-finals here last year, eased into round two with a 6-2 7-6 (2) 7-5 victory over Roberto Bautista Agut but there were defeats for former champion Stan Wawrinka and Canadian Denis Shapovalov.
