US Open 2011: Andy Murray beats Donald Young at the US Open

Andy Murray did his best to make up for lost time by racing to a 6-2 6-3 6-3 win over Donald Young in their delayed fourth-round match at the US Open.

The pair were originally scheduled to play on Tuesday but heavy rain meant that by the end of Wednesday they had managed just three games.

When play resumed on Thursday, Murray dominated from the outset and wrapped up victory in one hour and 58 minutes.

He will play big-serving American John Isner at 1700 BST on Friday.

Isner, the 28th seed, defeated 12th seed Gilles Simon 7-6 (7-2) 3-6 7-6 (7-2) 7-6 (7-4) on Court 17 to reach his first Grand Slam quarter-final.

When it first became clear that wildcard Young would be Murray's opponent in the last 16, the focus had been on the American's shock win in their only previous meeting earlier this year.

However, by the time the match began in earnest under blue skies on Thursday, the story had shifted to the scheduling problems caused by the weather.

Murray himself admitted he faced an "incredibly difficult task" to win the title, with four five-set matches in four days a possibility, and with that in mind he began in sharp fashion.

A 2-1 deficit from Wednesday was swiftly wiped out as the Scot reeled off the first seven games to take a stranglehold on the match.

Murray's progress slowed in the second set during a passage of five successive breaks of serve, but it was the world number four who came out 4-2 in front when Young sent a volley long.

Young double-faulted on break point for the third time to give up the second set, and two superb forehand passes looked to have given Murray the decisive break at 3-1 in the third.

The Briton's serve was still fragile though, with a first-serve percentage firmly below 50% allowing Young opportunities to get into his return games, and the American was soon level at 3-3 as he retained a slim hope of making a real match of it.

But Murray had too much class in the end, cracking another fierce cross-court backhand pass as he broke serve for the eighth time at 4-3 and going on to serve out a highly satisfactory win.

And the 24-year-old then headed straight from the Grandstand arena to the practice courts to work on his serve as the rain stayed away.

"I was a little bit frustrated in the middle of the second set because I was returning well, hitting the ball well from the back of the court and was giving him chances that I shouldn't have been just because of not serving well enough," said Murray.

The Briton will have been boosted by the announcement later on Thursday that the men's final will now be played on Monday, ensuring a day off on Sunday for the winning semi-finalists.