Stan Wawrinka expressed sympathy for injured opponent Dmitry Tursunov following the Russian's withdrawal from what had been a compelling Australian Open first-round match.
Fourth seed and 2014 champion Wawrinka was leading 7-6 (7-2) 6-3 on Tuesday when Tursunov, playing a first grand-slam match since 2014, retired with a hip injury having earlier needed a medical timeout.
It was a disappointing end for Tursunov, who had gone toe-to-toe with Wawrinka in the opener and earned a set point.
Wawrinka was happy to progress regardless of the circumstances, but the Swiss would rather have finished the match.
"That's not the way you want to win. You are never happy with an injury for an opponent, for sure. But that's part of the game," he said.
"I'm happy to get through the first round. I don't think he changed his game much because of the injury. I think after a little bit he couldn't really push more, so that's why he stopped.
"Before that he was playing his game the way he normally does."
Next up for Wawrinka is 37-year-old Radek Stepanek, and the world number four is expecting a tough encounter against the veteran.
"He is always a tough opponent. I played him last year in Tokyo and it was a tough match," Wawrinka added. "He's always playing good.
"It's quite a fast surface, so he should serve and volley, playing flat. [But] If I'm serving well, playing well and aggressive, hopefully I can make it through."