Injury-plagued Juan Martin del Potro on Wednesday underwent a third surgery on the right knee he broke at the 2018 Shanghai Masters and found immediate sympathy from world number one Novak Djokovic.
The 31-year-old Argentine giant has now had seven major operations in a career which promised so much when he swept to his first and only Grand Slam title at the 2009 US Open.
"In recent months, Delpo followed his doctors' advice and even tested the knee on a tennis court in Buenos Aires, but the pain persisted," said a spokesman.
"After their first meeting in Bern, Switzerland, (his surgeon) recommended a new surgery."
Del Potro, a former world number three but now down at 132 in the rankings, hasn't played since Queen's Club on the eve of Wimbledon in 2019.
As well as three knee operations, he had surgery on his right wrist in 2010 and three procedures on his left wrist in March 2014, January 2015 and June 2015.
Djokovic, whose 20-match rivalry with Del Potro stretches back 13 years, said he hoped to see the Argentine, a winner of 22 career titles, make a full recovery.
"I love and I support him and I send him my best wishes," said Djokovic after making the semi-finals of the Western and Southern Open in New York.
"He's probably one of the most unfortunate tennis players I have known with injuries. The quality of tennis that he possesses, it's really unfortunate to see him struggle so much.
"His fighting spirit and resilience to come back is something that's very inspiring. He's a gentle giant, a very likeable guy. I hope to see him soon."