Defending champion Novak Djokovic is through to the US Open semi-finals after a knee injury forced Jo-Wilfried Tsonga to quit when trailing 6-3 6-2.
Djokovic, 29, has completed just two of five matches in New York, benefiting from a walkover and two retirements.
He will face another Frenchman in the last four after Gael Monfils beat compatriot Lucas Pouille 6-4 6-3 6-3.
“This was the scenario that I needed and I wished for,” said Djokovic, who has faced his own health issues.
The Serbian world number one arrived at Flushing Meadows nursing injuries to both his left wrist and right elbow.
“I got a lot of days off and recovered my body,” he said. “Right now I’m feeling very close to the peak. That’s the position where I want to be.”
Second seed Andy Murray takes on Kei Nishikori on Wednesday, before Juan Martin del Potro and Stan Wawrinka play the last of the quarter-finals.
In the women’s draw on Tuesday, Denmark’s Caroline Wozniacki beat Anastasija Sevastova 6-0 6-2 in another match marred by injury, with the Latvian severely hampered by a twisted ankle.
Wozniacki won easily to set up a semi-final against German second seed Angelique Kerber, who beat Italy’s Roberta Vinci 7-5 6-0.