Top seed Rafael Nadal did not have it easy despite defeating Uzbekistan's Denis Istomin 6-2 7-6 (7-5) 7-5 at the US Open.
Istomin was two points away from claiming the second set in a tiebreak which featured a sensational rally that saw the unseeded man doing the splits after hitting a brilliant winner.
Istomin led 5-1 in the second set tiebreak before giving away the next six points as Nadal's composure and temperament came to the fore.
The eight-time major winner Nadal was impressive without starring, but will be delighted to have won this difficult match in three sets.
The Spaniard saved all seven break points he faced as he made the third round at Flushing Meadows for the sixth successive year.
Earlier, Andy Murray's march to a maiden Grand Slam continued after beating Dustin Brown 7-5 6-3 6-0 to reach the third round at the US Open.
The No.4 seed was momentarily rattled by his hard-hitting Jamaican opponent, losing two of his three challenges in Brown's opening service game as he struggled with Brown's powerful first serve and thumping forehands.
A rain delay halted the match midway through the first set before Murray gained the crucial break in the 12th game, bringing up two set points that Brown could not save.
The Briton raced to 5-0 in the second set as Brown twice failed to hold his serve, before the Jamaican hit back with a break of his own.
But it was too little too late as Murray held to wrap up the second set, then cruised through the third after breaking Brown's serve three times to wrap up the match in one hour 25 minutes.
Murray will face the winner of the match between Juan Ignacio Chela and Stanislas Wawrinka in the third round.
Meanwhile, No.10 seed David Ferrer will meet Daniel Gimeno-Traver in the third round after defeating Benjamin Becker 6-3 6-4 6-4.
No.18 seed John Isner is also through to the third round, the hometown hero battling his way past Marco Chiudinelli 6-3 3-6 7-6 6-4 in two hours 57 minutes.
Isner will next face 12th-seeded Russian Mikhail Youzhny.
Ukranian Sergiy Stakhovsky saved three match points on his way to an epic 3-6 7-5 6-3 3-6 6-7 (6-9) victory over American teenager Ryan Harrison.
Stakhovsky will meet No.23 seed Feliciano Lopez in the third round.