Juan Martin del Potro powered past Canadian Denis Shapovalov 7-5, 6-4 and into the second round of the Queen's Club Championships Wednesday as spells of rain again caused headaches for tournament organisers.
The Argentine sent down 11 aces and needed only two breaks of serve to beat world No. 25 Shapovalov on Centre Court but hurt his right knee after slipping near the net in the second set and finished the match with pain and swelling.
Del Potro fractured his right kneecap last October.
The Argentine player underwent tests after the match, with organizers later confirming his withdrawal from the Queen's Club event.
Wimbledon starts on July 1.
He is set to meet Feliciano Lopez in the next round after the Spanish veteran rallied from a set down to beat Hungary's Marton Fucsovics 6-7 (4), 6-3, 6-4. Frenchman Jeremy Chardy beat Mikhail Kukushkin 6-1, 6-3 before rain brought matches on all courts to a temporary halt.
Rain caused the cancellation of a full day's play Tuesday for the first time since the opening day of the 2012 tournament.
After action resumed, Stan Wawrinka sealed a comfortable 6-3, 6-4 victory over local hope Dan Evans while qualifier Aljaz Bedene got past Alex de Minaur 3-6, 6-4, 6-4.