Safe to say Milos Raonic's final tune-up tournament before the Olympics didn't go exactly as planned.

Raonic, seeded third at the Campbell's Hall of Fame Tennis Championship in Newport, Rhode Island, struggled again in his second-round match Tuesday, losing 6-3, 6-3 to qualifier Benjamin Becker of Germany Thursday.

The 21-year-old from Thornhill, Ont., was fortunate to even get to the second round after a sub-par showing in his tournament opener against Matthew Ebden of Australia. But Becker wouldn't let Raonic off the hook like Ebden did, cruising to the straight-set win that took just 63 minutes to complete.

"He didn't serve many aces, whereas last time I played him he served nearly 30 aces," Becker said. "His serve wasn't as effective today; I made him play a lot on his second serve and used my chances."

Raonic finished with just five aces -- his first serve percentage was just 50% -- and was broken three times. Becker, ranked 112th in the world, was dominant when he got his first serve in, winning 89% of the points, and saved the only two break points of the match.

Becker will play sixth-seed Ryan Harrison of the U.S. in the quarter-finals Friday.

Raonic, meanwhile, will return home to lick his wounds before heading to London for the Olympics. The men's singles competition gets under way July 28 at Wimbledon's All-England Club.