Novak Djokovic has signed a note of warning to his future opponents about his freshness, after easing into the US Open semifinals with another walkover.
The Serb was leading Jo-Wilfried Tsonga 6-3 6-2, until the Frenchman pulled out with a left knee injury.
Djokovic will play another Frenchman in Gael Monfils in the last four. The 10th seed had earlier beaten compatriot Lucas Pouille 6-4 6-3 6-3.
Djokovic has now spent just six hours and 28 minutes on court at Flushing Meadows after earlier withdrawals from Jiri Vesely and Mikhail Youzhny.
The extra rest has proven timely for Djokovic, who arrived in New York nursing injuries to both his left wrist and right elbow and the the top seed said: “I am not really concerned.
“Actually, in this stage of the season, considering some physical issues I have had in the last month, month and a half, this was the scenario that I needed and I wished for.
“I got a lot of days off and recovered my body. Right now I’m feeling very close to the peak. That’s the position where I want to be. This scenario was ideal at this stage. I’m reaching my peak in terms of my form.”