MONTREAL — It was a short, painful Rogers Cup for Milos Raonic.

The hard-serving Raonic, seeded sixth, lost 6-4, 6-4 to Frenchman Adrian Mannarino in his opening match on Wednesday night while playing through a left wrist injury that flared up this week.

"It's quite minor in the sense of 'can I get worse or not,' but it wasn't minor in the sense of quantity of pain," said Raonic. "I've been on anti-inflammatories to get the swelling down, not specifically painkillers.

"More just because my wrist at this moment, from the scanning I did, has quite a bit of fluid in it."

Raonic, of Thornhill, Ont., said he was confident it will heal in short order and that he will be fit for the U.S. Open at the end of the month.

He said he may have withdrawn from the tournament if it wasn't in his home country.

"I would have had definitely a different level of consideration to it, that's for sure," he said. "I definitely wanted to have a different storyline here.

"It wasn't necessarily the case. Hopefully I can turn it around very quickly because this was not a level of tennis to be proud of."