Venus Williams has suffered defeat in her comeback match at the Rogers Cup in Toronto, going down in three sets to Wimbledon semi-finalist Kirsten Flipkens in the first round.
The seven-time Grand Slam champion, who pulled out of the SW19 major in June with a back problem, had not played since her shock elimination in the opening stage of May's French Open.
Williams won the first set without dropping a game, but Flipkens recovered from that 6-0 drubbing to level the match by edging the second 6-4.
Fatigued then looked to be hampering Williams in the decider as her Belgian opponent raced into a 5-0 advantage, and despite the American threatening a comeback, Flipkens comfortably held on to claim victory in just under two hours.
The 13th seed will face Dutch qualifier Kiki Bertens in the next round.