Juan Martin del Potro faces a further lengthy injury layoff and will miss Wimbledon next month after fracturing the patella in his right knee for the second time in nine months.
The Argentine slipped on court towards the end of his first round win at Queen's Club in London over Denis Shapovalov on Wednesday and could also miss the US Open later this year.
"The medical studies done last night in a clinic in London show that Juan Martin del Potro has suffered again a fracture in the right patella," Del Potro's head of communications Jorge Viale tweeted on Thursday.
"After consultation with his doctor, Angel Cotorro, it has been determined that it will require surgery.
"This will take place in the next couple of days with a date and location to be determined."
Del Potro suffered the same injury after falling heavily in a match against Croat Borna Coric at the Shanghai Masters in October.
The world number 12 returned to action in February, but has been limited to just five tournament appearances this season and will not recover in time for Wimbledon which begins on July 1.
Del Potro's career has been ravaged by injuries, most notably to his left wrist that saw him sidelined for most of the 2014 and 2015 seasons.
However, he battled back to the top of the game, reaching the Olympic final and led Argentina to the Davis Cup title in 2016.
Despite losing his first Grand Slam final in nine years at Flushing Meadows in September to Novak Djokovic, Del Potro rose to number three in the world last year before being struck down again by injury.