Defending champion Andy Murray saw off Argentinean Leonardo Mayer 7-5, 6-1, 3-6, 6-1, to reach the third round of the US Open.
The Scot withstood some heavy hitting from his opponent at the Luis Armstrong Stadium, eventually overcoming the 81st seed in two hours, 41 minutes.
He sets up Germany’s Florian Mayer, the world number 47, in the last 32 on Sunday.
“I want to keep improving as the tournament goes on,” the third seed said. “You don’t want to play your best right at the beginning so I hope I can get better.”
Australian Lleyton Hewitt claimed the biggest surprise of the US Open men’s draw so far by beating sixth seed Juan-Martin Del Potro 6-4, 5-7, 3-6, 7-6 (7-2), 6-1 in four hours three minutes.
Elsewhere world number one Novak Djokovic beat Germany’s Benjamin Becker to reach the round of 32.
Czech Republic’s 5th seed Thomas Berdych overcame Denis Kudla of the United States 7-6 (7-3), 7-6 (7-3), 6-3 to reach the third round.
In the women’s draw defending champion Serena Williams beat Kazakhstan’s Yaroslava Shvedova 6-3, 6-1 in one hour 14 minutes to set up a meeting with fellow American Sloane Stephens.
In a repeat of last year’s US Open third round tie, China’s Li Na paid back Great Britain’s Laura Robson 6-2, 7-5 at the Arthur Ashe Stadium.
Sloane Stephens, who will face compatriot Williams in the round of 16, beat another fellow American Jamie Hampton 6-1, 6-3.
Agnieszka Radwanska of Poland saw off Russia’s Anastasia Palvyuchenkova 6-4, 7-6 (7-1) at the Louis Armstrong Stadium.
Germany’s Tommy Haas (12th seed) beat Thailand’s Yen-Hsun Lu 6-3, 6-4, 7-6 (7-3).
Ekaterina Marakova of Russia eliminated Wimbledon 2013 losing finalist, Sabine Lisicki of Germany, 6-4, 7-5.
Germany’s Florian Mayer beat Donald Young of the United States 7-5, 6-3, 6-4, setting up a third round clash with defending champion Andy Murray.
Carla Suarez Navarro of Spain defeated China’s Jie Zheng 6-2, 6-4.
Angelique Kerber of Germany cruised past Kaia Kanepi of Estonia 6-0, 6-4.
Jelena Jankovic of Serbia beat Japan’s Kurumi Nara 6-4, 7-6 (7-5).
Stanislas Wawrinka of Switzerland beat Ivo Karlovic of Croatia 7-5, 7-6 (10-8), 6-4.