The second seed, and defending champion, overcame an uneasy opening few games to win the match in three sets.
Rafael Nadal stutters into last 16 past David Nalbandian
Rafael Nadal, the defending champion, reached the last 16 of the US Open last night with a 7-6, 6-1, 7-5 victory over close friend David Nalbandian.
But it was an uneven performance from the second-seeded Spaniard, who endured a first set hiccup when he trailed the 76th-ranked Argentine 3-5, and was broken when he served for the match in the ninth game of the third.
Up next for the 10-time grand slam title winner is Gilles Muller, of Luxembourg, who eased past Russia's Igor Kunitsyn 6-1, 6-4, 6-4, for a place in the quarter-finals.
"It was a tough day. David is a fantastic player and a close friend who has had a tough time with injuries," said Nadal. "The first set was key when I came back when he was serving for the set. I am happy because I played my best match of the tournament so far."
Nalbandian, who reached No 3 in the world in 2006 before his career was stalled by hip and groin surgery, went into the tie with a 2-2 career record against Nadal.
And he was far from unbowed in the opening set when a game plan of all-out attack, which witnessed 18 winners and 23 unforced errors, almost paid dividends before the Spaniard played a more composed tie break.
That gruelling effort took an immediate toll on Nalbandian, who was broken three times in the second set. He stopped the rot with a surprise break in the opening game of the third, Nadal's concentration not helped by being hit with a time code violation for taking too long between points.
The Spaniard, bristling at the decision, took out his frustrations by breaking back before immediately calling a medical timeout for treatment on his blistered right foot.
Nadal was another break to the good on his way to a 5-2 lead before the dogged Nalbandian clawed back to 5-5, boosted by a break when the world No 2 served for the match at 5-3.
But the second seed held for 6-5 and claimed victory in the 12th game when Nalbandian, whose final error total climbed to 60, served up a seventh double fault.