World number four Andy Murray moved into the Monte Carlo Masters quarter-finals after France's Julien Benneteau retired from their third-round match on Thursday.
Murray was leading a fiercely contested opening set 6-5 when Benneteau quit, having fallen in the previous game when sliding to a wide ball and injuring his ankle.
Benneteau received lengthy treatment and took another injury timeout at the change of ends before deciding that he could not continue.
Murray was applauded as he brought ice bags to his opponent, who fell on the same spot of the court where Argentina's Juan Monaco badly sprained his ankle in his first round.
"The court, in parts, it's not flat, Murray told reporters.
"They said they had a few problems with it during the Davis Cup, but they changed it. Clay courts usually take a while, if you make changes to them, before they've kind of settled.
"That's probably why there were a few bad bounces and guys are kind of struggling with the movement a little bit."
Murray and the 31st-ranked Benneteau had produced some high-quality tennis to entertain the crowd for more than an hour on a sunny morning next to the Mediterranean.
Murray will take on Czech Tomas Berdych, the sixth seed, who defeated Kei Nishikori 2-6 6-2 6-4, recording his first win over the Japanese in three matches.
As the weather turned grey and cooled down, France's Jo-Wilfried Tsonga, the fourth seed, overcame a rain delay to beat Spaniard Fernando Verdasco 7-6 6-2.
The match was interrupted by a sudden downpour when Tsonga was ahead 3-2 in the opening set and another shower forced them back to the locker room after they returned to warm up.
Under light rain, Tsonga aggressively came to the net to claim two set points in the tiebreak before wrapping up the first set and he then cruised to a straightforward victory.
Tsonga will meet fellow countryman Gilles Simon, the ninth seed, who overcame Serbia's Janko Tipsarevic, the seventh seed, 6-0 4-6 6-1.
