Novak Djokovic says he hopes Juan Martin Del Potro will be able to return to competition after the Argentine underwent a third knee surgery on Wednesday.
Former US Open champion Del Potro broke his right patella in 2018 and refractured the kneecap during the Queen's Club Championships last year.
The former world No 3 has undergone three surgeries on his left wrist and another to his right but fought his way back to fitness each time to return to the Tour since winning the title at Flushing Meadows in 2009.
Djokovic said he could relate to Del Potro, having himself missed the last six months of the season in 2017 due to elbow problems.
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"He's probably one of the most unfortunate tennis players I have known with injuries," Djokovic said after his quarter-final victory in the Western & Southern Open.
"The quality of tennis that he possesses and with that much time that he had in career that he played, he already has amazing career, but, it's really unfortunate to see him struggle so much."
"His fighting spirit and resilience to come back is something that's very inspiring to me and to everyone else. He's a gentle giant, a very likeable guy," the 17-time Grand Slam champion added.
"I know there is probably no one that wants to play tennis more than him right now, and he's, I'm sure, doing everything he possibly can."
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