Adrian Mannarino gave third seed Andy Murray a huge scare in the second round of the US Open, while a former champion took his final bow at Flushing Meadows.

Murray triumphed 5-7 4-6 6-1 6-3 6-1 over Mannarino in three hours, 21 minutes, while Australian veteran Lleyton Hewitt went close to extending his final US Open singles appearance only to lose 6-3 6-2 3-6 5-7 7-5 to compatriot Bernard Tomic.

In a portent of things to come, Murray dropped serve in the opening game of his clash with the world number 35 as Mannarino scrapped his way to a two-set lead in New York.

Mannarino timed his run perfectly in the first two sets, winning the last three games of each to put Murray in desperate trouble in less than two hours.

But that was as good as it got for the Frenchman, with Murray blitzing the third set in just 32 minutes to set up his victory.

The Brit was one of four top-six seeds to progress on Thursday, with Roger Federer crushing Belgium's Steve Darcis, Stan Wawrinka edging past Chung Hyeon of South Korea and Tomas Berdych defeating Jurgen Melzer of Austria.

Second seed Federer won 6-1 6-2 6-1, while Wawrinka had a much tougher encounter against Chung with the Swiss fifth seed triumphing 7-6 (7-2) 7-6 (7-4) 7-6 (8-6), while sixth seed Berdych prevailed 7-6 (7-2) 6-1 6-3.

In the last match to be completed, Hewitt produced a quintessential comeback to force a fifth set against Tomic but could not overcome the man 12 years his junior.

Tomic was cruising at two sets up, 2-0 in the third but Hewitt reeled off six of the next seven games, losing just two points in four service games to stay alive.

The 2001 US Open champion - who will retire from professional tennis after next year's Australian Open - again fought back from 2-0 down in the fourth to take the match into a fifth set, and served for a spot in the third round at 5-4 up.

But Tomic survived two match points and then scrapped his way into his own winning position, eventually prevailing in 3:30 with a forehand winner.

Jiri Vesely and Ivo Karlovic completed the other five-setter on Thursday, with the former winning 7-6 (7-3) 3-6 3-6 6-2 7-6 (7-4), while Richard Gasquet defeated Robin Haase 4-6 6-3 7-6 (7-4) 6-4.

Belgium's Ruben Bemelmans and Dominic Thiem of Austria both benefited from retirements against Jack Sock and Denis Istomin, respectively, while Viktor Troicki, Donald Young, Guillermo Garcia-Lopez, John Isner, Kevin Anderson and Philipp Kohlschreiber also advanced.