Nadal holds off Querrey

Rafael Nadal looked far from invincible as he survived a serious challenge from Sam Querrey on Monday to advance to the quarter-finals of the US Open.

Top seed Nadal took over three hours to dispose of the 20-year-old American 6-2 5-7 7-6 (7/2) 6-3 to move one step closer to another possible showdown with second seed Roger Federer.

Nadal appeared to be heading for an easy win after building a 4-2 lead with a break in the second set but Querrey broke twice to level the match. Spaniard Nadal rallied to win a third-set tie-break and went on to take the final to set up a quarter-final clash with Mardy Fish.

American Fish progressed to the last eight after continuing his surprising run at Flushing Meadows with a 7-5 6-2 6-2 rout of 32nd seed Gael Monfils.

Sixth seed Andy Murray of Britain cruised through to the quarter-finals, beating Switzerland's Stanislas Wawrinka 6-1 6-3 6-3.

The 21-year-old easily disposed of Wawrinka in one hour and 49 minutes thanks to 38 winners and 37 unforced errors by the number 10 seed.

Murray took advantage of six of 13 break opportunities and held off three break chances by Wawrinka, who could not match the uptempo play of Murray after a gruelling five-set win over Italian Flavio Cipolla in round three.

Murray moved into the round of 16 for the first time in his three appearances at the US Open, where he will face 19-year-old Juan Martin del Potro of Argentina.

In a battle of talented teenagers, del Potro emerged with a 6-3 6-4 6-3 victory over 18-year-old Kei Nishikori of Japan.