Milos Raonic's best just wasn't good enough against Olympic champion Andy Murray.

The native of Thornhill, Ont., lost to Murray 6-4, 6-4, 6-2 on Monday in the fourth round of the U.S. Open.

"It was a tough match, he was just too good," said Raonic. "I was never comfortable and he played extremely well. This was a big loss, I really gave everything out there and I've never felt such a defeat."

Murray, still seeking his first Grand Slam title, reached the quarter-finals at an eighth consecutive major tournament by beating the 15th-seeded Raonic.

'This was a big loss, I really gave everything out there and I've never felt such a defeat.'— Milos Raonic after losing to Andy Murray at the U.S. Open

Raonic was trying to become the first Canadian man in a Grand Slam quarter-final in the Open era, which began in 1968.

Canadian women remain the only players to have gone to the last eight in a Grand Slam, most recently through Patricia Hy-Boulais at the 1992 U.S. Open.

Raonic reached this stage at a major for the second time after getting to the last 16 from a qualifying start at the Australian Open last year.

"This was my eighth Grand Slam and I'm pretty new to this," said Raonic. "I've only played here twice. Sometimes I get frustrated with myself."

Raonic is the third Canadian to reach the round of 16 at a Grand Slam in the Open era, after Montreal's Martin Laurendeau at the 1988 US Open and Toronto's Daniel Nestor at Wimbledon in 1999.

Learning experience

He stands 1-7 against top five opponents, with his only win coming against Murray on clay in Barcelona last spring.

"I need to improve a lot of things in my game if I'm going to compete with guys at the top level," said Raonic. "But I also want to learn as much as I can. Every experience at this level is a new one. I have to deal with them the best I can."

Despite his disappointment, Raonic will rise to an ATP ranking of around 14th next Monday.

Raonic never got a break point on the Murray serve and managed only 14 aces — about half his average at the event in the first three rounds. He converted on three of 11 break points and lost his own serve four times in a disappointing evening.

"I felt like I was doing it well most of the time, except maybe a few shots I didn't go for as much in the beginning just because I didn't know how to really read it," said Raonic.

The match was moved to an earlier start because of rain clouds moving into the area, but the contest concluded without interruption.

"It's tough in there (Arthur Ashe Stadium), it's something I haven't really experienced," said Raonic. "It's windy constantly and coming from all different directions. So it was hard to really just step in on the ball."

Murray played smart tennis to nullify Raonic's huge serve, using his returning skills to dominate.

The third-seeded Murray created his first chances in the eighth game of the opening set, forcing Raonic to save two break points before finally dropping serve for 3-5.

A game later, Murray secured the set on his second opportunity from a Raonic return wide.

The balance of power stayed the same in the second set. Raonic lost serve for 2-3 after again saving two break points but failing on a third.

Raonic managed to save a pair of set points, holding serve for 4-5 before Murray took a two-sets-to-love lead as he fired an ace on the first of three more match points, a shot which Raonic unsuccessfully challenged with the electronic linecalling system.

The third set was all Murray, with Raonic struggling to no avail as the Scot closed out the win thanks to breaks in the third and seventh games, sealing it on his first match point from Raonic's return long.

Murray, the 2008 U.S. Open runner-up, and his coach, Ivan Lendl, are the only men to lose their first four major finals.

Next for Murray is a match against No. 12 Marin Cilic. Murray leads their head-to-head series 6-1, but his only loss to Cilic came at Flushing Meadows in the fourth round in 2009.

Double bagels

Meanwhile, Serena Williams didn't drop a game in advancing to the quarterfinals. Roger Federer moved on with even less work when Mardy Fish pulled out of their fourth-round match for precautionary reasons.

Fish missed about two months this season because of an accelerated heartbeat and had a medical procedure in May. His agent, John Tobias, said "we are not 100 per cent sure what the issue is and if it is related to his previous issues."

"I was reluctant to do so, but am following medical advisement," Fish said about his withdrawal in a statement. "I had a good summer and look forward to resuming my tournament schedule in the fall."

The 30-year-old American's third-round match against Gilles Simon went five sets, lasting more than 3 hours and ending after 1 a.m. Sunday. Afterward, the 23rd-seeded Fish did not appear at a news conference. Tournament officials said he was getting treatment, but didn't give specifics.

"I am really sorry for Mardy. I just want to wish him a speedy recovery," Federer said in a statement. "We all want to see him back on tour soon."

Williams beat 82nd-ranked Andrea Hlavackova 6-0, 6-0 in 57 minutes. It was the first time in 62 career victories at Flushing Meadows that the three-time U.S. Open champion enjoyed a "double bagel."

"She was fighting really hard," Williams said. "You give people any type of chance, especially in tennis, the match is never over until you shake hands. There is always a comeback available. So I didn't want to give her that opportunity — or anyone that opportunity — to try to come back, especially her in particular. She was getting so pumped up and she never gave up. I thought that was really incredibly positive."

Williams had 31 winners and just seven unforced errors. She and sister Venus play doubles during Monday's night session in Arthur Ashe Stadium.

Hlavackova, a 2011 French Open doubles champion, had never been past the second round in singles at a major tournament before this year.

Ivanovic next for Williams

Williams will next face Ana Ivanovic, who is finally back in a Grand Slam quarterfinal more than four years after her French Open title.

The 12th-seeded Serb beat Tsvetana Pironkova 6-0, 6-4. Ranked No. 1 in the world in 2008, Ivanovic has struggled with injuries and her confidence since.

"There were some good moments and some tough ones, but it's a process. I understand it better now," she said. "There are times when you realize that it's exactly what it is: It's a process. You can't have everything at the same time. You have to be consistent on practice courts and then in the matches."

After failing to serve out the match at 5-3 in the second set, Ivanovic broke the 55th-ranked Bulgarian at love in the next game to clinch the victory.

Pironkova, a 2010 Wimbledon semifinalist, went up a break twice in the second set only for Ivanovic to immediately break back. There were seven service breaks in 10 games in the set.

Pironkova held serve just once in the match. Ivanovic had more success on Pironkova's first serve than her own. The Serb won 65 per cent of the points when her opponent got in her first serve, compared with 61 per cent when her own first serve landed in.

Italian doubles partners Sara Errani and Roberta Vinci each won to set up a meeting in the quarterfinals. Vinci upset second-seeded Agnieszka Radwanska 6-1, 6-4.

Federer, in his 34th consecutive quarterfinal at a major tournament, will meet sixth-seeded Tomas Berdych, who defeated 11th-seeded Nicolas Almagro 7-6 (4), 6-4, 6-1 in 2 hours.

"At least good that I didn't stay that long on court, that I was able to save some energy, as well," Berdych said.