World No.1 Roger Federer had a walkover while third seed Andy Murray breezed past Canada’s Milos Raonic as both reached the quarter-finals of the US Open on Monday.

Federer advanced to his 34th consecutive grand slam quarter-final without touching a racquet when American Mardy Fish withdrew from their US Open match for health reasons.

The 31-year-old Swiss star, seeking his 18th grand slam title and sixth US Open crown, moved through to a last-eight match-up against Czech sixth seed Tomas Berdych, who dispatched Spanish 11th seed Nicolas Almagro 7-6 (7-4) 6-4 6-1.

The walkover stretched Federer’s record for quarter-final grand slam appearances in the Open era to 38, three shy of the record 41 achieved by American Jimmy Connors.

Federer, who won his 17th grand slam title in July at Wimbledon, has not dropped a set in the Flushing Meadows fortnight.

Fish missed two months of the season earlier this year because of a heart problem, being hospitalised after the Miami Masters event in March when his heart rate increased to three times its normal resting pace.

Fish, 30, then had a cardiac catheter ablation in Los Angeles on May 23 to address his heart condition.

“I regret that I have to withdraw from the US Open for precautionary measures,” Fish said.

“I was reluctant to do so, but am following medical advice.

“I had a good summer and look forward to resuming my tournament schedule in the fall.”

Federer said he was sorry to see Fish forced to withdraw from their encounter.

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

Berdych, who took only two hours to reach his first US Open quarter-final, has lost 11 of 15 career meetings to top seed Federer but won three of his past six meetings.

Berdych finally reached the last eight after 10 tries with his 200th career hardcourt triumph. He joined Petr Korda and Ivan Lendl as the only Czech men in the Open era to have reached the quarter-finals at all four grand slam events.

“I’m very happy that I can compete in all grand slams at least in quarter-finals. It helps my confidence,” Berdych said.

Murray booked his spot with a comfortable 6-4 6-4 6-2 win over 15th seed Raonic.

Olympic champion Murray, seeking his first grand slam title, will play for a berth in the semi-finals against Croatian 12th seed Marin Cilic.