Rafael Nadal breezed into the third round of the U.S. Open, as the defending champion was two sets to the good when Nicolas Mahut retired on Friday.

Rafael Nadal of Spain hits balls in the crowd after after his opponent Nicolas Mahut of France retired with an injury at the U.S. Open tennis tournament in New York, September 2, 2011. [Xinhua]

Mahut elected to serve and volley, offering Nadal a different challenge to what he normally faces, but it made no difference as the Frenchman only turned himself into a target at the net for Nadal to pass.

The Spaniard, who has not been at his best this season, crunched 24 winners and broke serve on four occasions as he secured safe passage into round three in a shade over an hour and a quarter.

Andy Murray overcame a two-set deficit to defeat Robin Haase and advance to the third round with a 6-7(5), 2-6, 6-2, 6-0, 6-4 victory.

The fourth-seeded Murray led 4-0 in the fifth set but Haase won four straight games.

Serving at 5-4, Murray had match point and Haase hit a forehand that was called out. Haase challenged and the replay showed the ball barely clipped the line.

But Murray answered with a pair of service winners on the next two points to close out the match.

Murray has been in the semifinals of the year's first three majors but is still in search of his first Grand Slam title.

His next match is against No. 25 Feliciano Lopez of Spain, who beat Canadian Vasek Pospisil 5-7, 6-4, 7-6(3), 7-6(5).

Former champion Juan Martin Del Potro backed up his impressive first-round win over Filippo Volandri with a mauling of fellow Argentine Diego Jungueira.

The 18th seed has not been beaten at Flushing Meadows since 2008, having been denied the chance to defend the title he won in 2009 on account of injury, and it could be some time before he is beaten again judged on his 6-2, 6-1, 7-5 win.

The Argentine's game is built on a powerful serve and crunching forehand and for two sets he was in full working order, as he dropped just eight points in serve.

Fifth seeded David Ferrer easily cruised past American veteran James Blake to a 6-4, 6-3, 6-4 victory.

The Spaniard hit fewer aces and winners than his American counterpart, but Blake tallied 51 unforced errors for the match.

John Isner, No. 28 seed, won the battle of the Americans, blasting down 20 aces in his 6-4, 6-3, 6-4 win over Robby Ginepri.

Donald Young gave the home fans surprising cheers as the American battled relentlessly to beat Stanislas Wawrinka, seeded 14, in five sets. Young won both tiebreakers in a epic victory of 7-6(7), 3-6, 2-6, 6-3, 7-6 (1).

In other second round match up, 12th seeded Gilles Simon of France defeated Guillermo Garcia-Lopez of Spain 6-4, 6-7(4), 7-5, 6-3.

Julien Benneteau from France shot down Denis Istomin of Uzbekistan in straight sets of 6-4, 6-4, 6-4

David Nalbandian of Argentina outperformed 30th seeded Ivan Ljubicic of Croatia 6-4, 1-6, 6-3, 6-2.

Another Argentinean, 24th seeded Juan Ignacio Chela powered off Steve Darcis of Belgium 6-2, 6-4, 6-4.

Russia's Igor Kunitsyn fought through five sets to win over 17th seeded Austrian Jurgen Melzer 3-6, 6-3, 1-6, 6-2, 7-6(5).

Gilles Muller of Luxemburg beat Ernests Gulbis from Latvia, 3-6, 7-6 (4), 6-4, 7-6(5).