The Canadian, 20, destroyed the double Olympic champion in ruthless style to win 6-2 6-3 6-4 in two hours and seven minutes.
The No.15 seed hit 52 winners – versus only nine by Murray – and did not face a break point.
It was a chastening loss for Murray, 33, in his first Grand Slam back with a metal hip.
But the three-time Major winner, who was playing only his second event of the year, stated: “I would say even after tonight I’m more positive about what I could do in Grand Slams than I was before I came over here.
“You guys obviously don’t know how I was feeling even just a couple of months ago. “So to come over here and play, you know, I played a couple of tough matches in Cincinnati and I played certainly one very tough match here, and my right hip felt good. That’s really, really positive.
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“There are other things that need to get better, but I would say that I’m more positive now than what I was a couple of months ago, that’s for sure.
“In terms of winning Grand Slams again, that’s going to be extremely difficult to do.
“It was hard enough when I had two normal hips. So it will be difficult, but I’ll keep trying, like, why not? Why shouldn’t I try my hardest to do that? And if I don’t, that’s all right. But I might as well shoot for the stars. And if I don’t get there, then that’s all right. But I’m trying my best to get the most out of what my body gives me now.
“I’m ranked 115, 120 in the world and my game reflects that just now. So I’ll need to get better if I want to move up the rankings and be more competitive.”
Murray defeated world No.7 Alex Zverev at the Western & Southern Open last week and came through an epic five-set victory over Yoshihito Nishioka in the first round.
And he now plans to fly home before playing the French Open which begins on September 27.
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