Kyle Edmund crashed out of the Rogers Cup in the opening round, suffering a bruising 6-1 6-2 loss to Diego Schwartzman.
After rain delayed play, the British No 1 was dismissed in an hour by the Argentine No 11 seed on Monday evening.
Edmund appeared outgunned by Schwartzman from the off, losing his first service game as the world No 12 raced into a 3-0 lead.
The Briton, ranked 16th by the ATP, made it on to the scoreboard in the fourth game, but was broken again in the sixth and went on to lose the set.
Edmund, who after a bye was knocked out in the second round of the Citi Open by Andy Murray a week ago, appeared to have regained some composure as play resumed.
However, with the second set level at 2-2, Schwartzman broke the Briton's serve then reeled off the next three games to close out the match.
Canadian Milos Raonic made good use of his booming serves to dump out 10th seeded Belgian David Goffin.
Playing in front of his home supporters, Raonic toppled Goffin 6-3 6-4, winning all 27 of the points scored while he was on first serve.
"I think I can still serve much better," Raonic told reporters after needing only 73 minutes to advance. "The way I was aggressive from the baseline, I hit my forehand well. It's something we spent these last two weeks working on."
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