Murray, three times a semi-finalist, wore down France's world number 164 Mathias Bourgue, who had never won a tour-level match before this week, 6-2, 2-6, 4-6, 6-2, 6-3 and goes on to face 37-year-old Ivo Karlovic for a place in the last 16.
After coming back from two sets to love down to beat Radek Stepanek, also 37, in the first round in a tie played over two days, the British star had looked down and out once again yesterday.
After pocketing the third set, 22-year-old Bourgue, reduced to tears by the end, had break points for a 1-0 lead in the fourth.
But once they were squandered, the Frenchman's challenge quickly wilted as the physically stronger Murray raced away with 12 of the last 15 games.
"He was excellent today. He dictated the points and made me run. He's going to have a fantastic future," said Murray after escaping what would have been his worst loss at the majors since a first round exit at the 2008 Australian Open.

“At the end of the third set, I just thought what happened? I was 6-2, 2-0 ahead. He was then unbelievable and I found it hard just to win points,” he added.

"But I have played these matches many times. I just tried to fight through."

As an indication of his struggles, yesterday was the first time since the US Open in 2005 that Murray had played two successive five-set matches at the Slams.
Karlovic, the 27th seed, defeated Australian wildcard Jordan Thompson 6-7 (2/7), 6-3, 7-6 (7/3), 6-7 (4/7), 12-10 in a four and a half hour marathon, unleashing 41 aces and 102 winners.
Karlovic is the oldest man in the French Open third round since 38-year-old Jimmy Connors in 1991.

Defending champion and third seed Stan Wawrinka defeated New York-born Taro Daniel of Japan 7-6 (9/7), 6-3, 6-4 and goes on to face France's Jeremy Chardy.
"When you play a French player in Paris, it is always a bit different because the French are at home," said Wawrinka of Chardy who he has beaten all four times they have met.
Japan's fifth seed Kei Nishikori, a quarter-finalist in 2015, coasted into the last 32 with a 6-3, 6-3, 6-3 victory over Russia's Andrey Kuznetsov. Nishikori, the 2014 US Open runner-up, goes on to face former world number seven Fernando Verdasco of Spain.

Australian 17th seed Nick Kyrgios needed just 70 minutes to beat Dutch lucky loser Igor Sijsling 6-3, 6-2, 6-1.

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