NEW YORK — Milos Raonic didn't have his main weapon ready to bail him out at Flushing Meadows.

The fifth-seeded Raonic crashed out of the U.S. Open in the second round Wednesday, losing 6-7 (4), 7-5, 7-5, 6-1 to unseeded Ryan Harrison, a qualifier ranked 120th.

Raonic had problems holding serve, usually a strength for the six-foot-five Canadian, and double faulted 15 times. Raonic looked defeated after Harrison broke for the fifth time to win the third set.

"I didn't serve well to start this tournament and that's normally my go-to that can keep me out of situations," said Raonic.

"I think that added a little bit more (stress) than I normally have to deal with and I think that caught up to me throughout that match."

The American broke Raonic seven times on 18 chances to improve to 2-1 in the career head-to-head series between the players.

Raonic still managed to fire 18 aces. But he also made 66 unforced errors to Harrison's 33 and only converted three of 19 break point opportunities.

The product of Thornhill, Ont., didn't feel 100 per cent for most of the match. He said it was more than just some cramping that altered his play.

"Numerous things — left arm, right forearm towards the end of the third set, both quads, hip flexor on the left," said Raonic.

"Really painful cramps started to pass in the third set but then I got small ones where I couldn't hold the raquet and switch grips from one shot to the next."

Harrison will face Marcos Baghdatis of Cyprus in the next round.

With Raonic's unexpected early exit, there are no Canadians left in the singles draws.

Earlier Vancouver's Vasek Pospisil was eliminated after a 7-6 (3), 6-4, 6-4 loss to 23rd-seed Kevin Anderson of South Africa.

Pospisil started the match with a break in the first game, but Anderson recovered with a break in the next game and won a back-and-forth first set in a tiebreaker.

Anderson won the next two sets comfortably to advance to the third round.

Pospisil struggled in singles play at Grand Slam events this year, with his only victory at a major coming Monday when he defeated Jozef Kovalik 6-1, 6-3, 6-3 in the first round.