Andy Murray of Britain lunges for a shot against Robin Haase of the Netherlands during their match at the U.S. Open tennis tournament in New York. Picture - Reuters.

World number two Rafael Nadal and number four Andy Murray both progressed to the third round of the US Open, although in very contrasting circumstances.

Nadal was soaring with a two set lead (6-2 6-2) when Nicolas Mahut retired with an abdominal injury.

Murray, on the other hand, had to fight back from two sets down to beat Dutchman Robin Haase.

The Scot won 6-7 (5-7) 2-6 6-2 6-0 6-4 at the Louis Armstrong Stadium and will face 25th seed Feliciano Lopez in the third round.

Murray can consider himself fortunate to come through with a win as he was poor for the first two hours of the match. At two sets down though, he found his rhythm and movement and staged a commendable comeback.

Hasse broke first in the opening set at 3-3 only but was broken back when he should have closed out the set. It went into a tie-breaker in which Murray gained the upper-hand after going 4-1 up. However, Haase then took five points in a row before converting his second set point.

Murray made nineteen unforced errors in the first set and things didn't start off well for him in the second as he dropped serve in the opening game. Hasse held, and although Murray managed to break back in game five, he double-faulted in the very next game, helping a confident Hasse break again to take the second.

When the Scot fought back from 40-0 down to break in the third set, it was evident that it was the turning point of the match. Murray let out a roar and suddenly he was on top, regaining his forehand and covering a lot of ground. He broke once again to secure the set.

In the fourth, Haase injured his back and after returning from a lengthy treatment, he let a 40-0 lead slip. It only helped a hyper Murray take the fourth. The Scot took 13 games in a row against a tired Dutchman, as he surged into a 4-0 lead in the final set.

It was then that Haase staged his own comeback to make it 4-4 although he failed to back it up as he dropped serve with a tired service, handing Murray the chance to serve out the game.

And the drama wasn't over yet. Murray double-faulted, for the eighth time, and just about survived a break point as Haase could only return the second serve into the net. The Dutchman then sent a return long, finally ending the match.

Afterwards, Murray admitted that if he played in the same manner as he did in the first two hours against Hasse, he wouldn't last long in the tournament.

It was a tough match and if I play like I did today I might be going home, said Murray. Maybe I should have won the first set tie-break, I need to make sure I'm moving well in the next match otherwise it's bad news.

I just wasn't playing well (in the beginning of the match), I was moving really poorly and that's not good for my game. Once I started to move better towards the end of the third set my game was so much better.

Elsewhere, there was an early upset in the women's game.

Third seed Maria Sharapova crashed out from the tournament as Italy's Flavia Pennetta secured a shock third-round win. 

The 26th seed Pannetta won 6-3 3-6 6-4 at the Arthur Ashe Stadium as Sharapova, one of the favourites for the win, failed to meet expectations.