Rafael Nadal, Andy Murray and Americans Andy Roddick and John Isner have advanced to the quarter-finals of the 2011 U.S. Open.
Nadal faced a stiff challenge from Luxembourg's Gilles Muller, who pushed the second-seeded Nadal to a tiebreaker in the 65-minute first set before the Spaniard breezed through the final two sets in a total of 63 minutes. Nadal won on 73% of his first serves, while Muller committed 43 unforced errors. No. 4-seed Murray needed just under two hours to dispose of American Donald Young in straight sets 6-2, 6-3, 6-3.
No. 21 Roddick and No. 28 Isner needed four sets to advance to the quarter-finals. Roddick took a two-set lead on No. 5 David Ferrer of Spain before dropping the third set 6-3. Roddick responded with a 6-3 win in the final set. The 26-year-old Isner needed a little over three hours to upset No. 12 Gilles Simon of France, winning all three of his sets via tiebreakers.
Roddick and Isner advancing gives the United States two U.S. Open quarter-finalists for the first time since 2008. Roddick's next match will be against Nadal, while Isner draws Murray.