German second seed Alexander Zverev saved a match point and survived a second successive French Open scare on Friday, coming back to defeat Bosnia's Damir Dzumhur 6-2, 3-6, 4-6, 7-6 (7/3), 7-5 to reach the fourth round for the first time.
Zverev, 21, who is seen as Rafael Nadal's principal obstacle to the Spaniard's expected coronation as champion for an 11th time, endured a nightmare outing before claiming victory after almost four hours on Court Philippe Chatrier.
He hit 73 unforced errors, dropped serve eight times and served up seven double faults.
He had to save a match point in the 10th game of the decider before breaking and holding to make the last-16 where he will face either French 15th seed Lucas Pouille or Russia's Karen Khachanov.
"It was an amazing, high level match, it was the first time I have won on this court and I hope there are many more to come," said Zverev, bidding to become the first German men's champion in Paris since 1937. Dzumhur, the 26th seed, was left to regret squandering a host of opportunities.
He served for the match at 6-5 in the fourth set only to be broken to love before battling back from 1-3 down in the decider to go to match point at 5-5.
That was saved by a nerveless out-wide serve from the German who held, then broke for 6-5 before claiming victory when the Bosnian hit long.
Dzumhur finished with 51 winners — the same as Zverev — but 68 unforced errors and was broken nine times.
"All I could do was keep fighting," said Zverev who had also needed five sets to beat Serbia's Dusan Lajovic in the second round.
He has now equalled his best ever Slam performance after also making the fourth round at Wimbledon last year. Speaking further about the win he added: "He served for the match and I had to save lots of break points in the fourth and fifth sets. Sometimes you have to battle to get the win and that's what I did today."
For Zverev it was a 33rd win of the season, the best figures on the tour which has also yielded clay court titles in Munich and Madrid as well as a runners-up spot to Nadal in Rome.
In a dramatic — if error-plagued match — there was a worrying moment when Dzumhur accidentally collided with a ball boy as they both chased an airborne dead ball after two games of the fourth set.
The distressed youngster needed to leave Court Philippe Chatrier after receiving a consoling hug from the Bosnian player.