09/02/2012 02:38 EDT | Updated 11/02/2012 05:12 EDT

Raonic's confidence high before fourth-round US Open match against Murray

TORONTO - Milos Raonic says he's gaining more confidence with every victory at the U.S. Open. He'll need it all to reach his first Grand Slam quarter-final.

Raonic takes on Olympic champion and third seed Andy Murray in fourth-round action Monday. Murray will be looking for payback after Raonic upset him in the quarter-finals at a tournament in Barcelona earlier this year.

Early at Flushing Meadows it looked like Raonic may not even get to this point. The tournament's 15th seed from Thornhill, Ont., struggled mightily in the first round in a five-set win over world No. 46 Santiago Giraldo.

He recovered impressively and won his next two games in straight sets with his powerful serve, firing 30 aces in his second-round win over Paul-Henri Mathieu and 29 in his third-round victory over James Blake.

"I definitely struggled early in this tournament. It was lucky to get by the first one," Raonic said Sunday on a conference call from New York. "Then I got better in the second round and I felt I started to play really well.

"(The confidence) is definitely building up at the same time as my game. I'm doing more and more things I want to be doing and my serve's helping me a lot with that."

The last time Murray and Raonic faced each other was on the clay surface of the Barcelona Open, where Raonic posted a stunning 6-4, 7-6 (3) victory.

It will be different on the hardcourts of Flushing Meadows, which favour Murray's all-round game. While the Scot hasn't won a Grand Slam yet, he has reached a U.S. Open final and has twice been a finalist at the Australian Open, which is also a hardcourt event.

However, Raonic's greatest weapon is his serve, which will be more dangerous on the fast hardcourt than on the deadening clay of Barcelona.

"I think I'm just going to have to really go for it and go after him and try to control as much as I can," he said. "I think on the hardcourt I'll have more opportunities to do so, and I feel if I do that and I serve well then I'll definitely have my opportunities."

Raonic said tightness in his game contributed to his slow start, but he has been able to put that behind him with two strong wins.

"Because I wasn't playing well and I wanted to do well I was playing tight, and even though it was just a three-and-a-half hour match it felt a lot bore tiring because I was so uptight the whole match," he said.

"I know how to fight, I know I'm competitive, and I was fortunate to be able to find my way out of that."

A win against Murray would put Raonic in a semifinal against either 12th-seeded Marin Cilic or unseeded Martin Klizan, giving him a realistic to advance to a possible semifinal match with top-ranked Roger Federer.