REUTERS: Juan Martin del Potro powered past Canadian Denis Shapovalov 7-5 6-4 and into the second round of the Queen's Club Championships on Wednesday as spells of rain again caused headaches for the tournament organisers.
The Argentine sent down 11 aces and needed only two breaks of serve to beat world number 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, who fractured his right kneecap last October, was scheduled to undergo tests on Wednesday.
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 on Tuesday for the first time since the opening day of the 2012 tournament.
After action resumed a little before 1700 GMT, Swiss 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.
However, rain stopped play again with Stefanos Tsitsipas leading Briton Kyle Edmund 6-3 3-3 as the organisers pushed matches back to Thursday where action will begin at 1000 GMT.
(Reporting by Shrivathsa Sridhar in Bengaluru; Editing by Toby Davis)