Murray triumphed 5-7, 4-6, 6-1, 6-3, 6-1 after his world number 35 opponent had threatened to condemn him to his earliest loss in New York since also making the second round on debut in 2005.

But left-hander Mannarino wilted in the 30-degree heat and humidity in Arthur Ashe Stadium as Murray's greater freshness and physical condition proved crucial.

Murray goes on to face Brazilian 30th seed Thomaz Bellucci for a place in the last 16.

"It was extremely tough. He hits the ball really flat, has fantastic timing on both sides and it was hard to read the ball in the first two sets," said 28-year-old Murray after his eighth career comeback from two sets to love down.

"I was leaving the ball too short and he made me do a lot of running."

Murray, who had needed four sets to beat Nick Kyrgios in the opening round, fired 21 aces - the last of which was on match point - while Mannarino was undone by 61 unforced errors.

It was a familiar tale of woe for the 27-year-old Frenchman, who also had a two sets to love lead over Feliciano Lopez at the Australian Open in January before retiring with heat exhaustion in the fourth set.

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