Five-time champion Rafael Nadal narrowly avoided falling victim to a stunning upset as he fought back to beat John Isner in the first round of the French Open.
The 6ft 10in American looked on course for a victory that would have outdone even his world-record 11-hour match at Wimbledon last year, but Nadal recovered from two sets to one down to win 6-4 6-7 (2-7) 6-7 (2-7) 6-2 6-4.
Defeat would have been the first time that a reigning French Open champion had lost in the first round, and it would have ensured that Nadal lost his number one ranking to Novak Djokovic after the tournament.
It would also have been only the second time Nadal had been beaten at Roland Garros. That previous defeat came against Robin Soderling two years ago, a result the Spaniard avenged in last year's final, and he came to Paris this year looking to equal Bjorn Borg's record of six titles.
Djokovic, unbeaten this year, appears to be a real threat to Nadal's domination of the tournament, but few can have expected Isner to push him so close.
At 39 in the world, the American was the highest-ranked player Nadal had ever been drawn against in the first round at Roland Garros, but he has been enduring an average season and slipped from 31 in the world in January.
The much-discussed new balls being used at Roland Garros this year - which most of the players say are flying faster than normal - must have played into Isner's hands, but he hit a relatively modest 13 aces to Nadal's eight and won fewer points on his first serve.
Isner showed the same heart he had displayed at Wimbledon last year to haul himself back from a set and a break down, and when he levelled matters in the second set tie-break the full weight of the Court Philippe Chatrier crowd moved behind him.
A drop shot at the start of the third set saved a break point as Nadal pressed and a couple of deft drop-volleys did the same in game eight, before two thunderous serves saw off set points in game 11.
That serve came to the fore once again in the tie-break, something of an Isner speciality, and he dominated it to move into the lead and leave Nadal looking momentarily lost for answers.
But sheer guts and determination are what the Spaniard can always fall back on in times of crisis and he was in full fist-pumping flow in the fourth set, breaking twice and not making a single unforced error as he forced a fifth set - his first ever at the French Open.
Isner appeared to be running out of steam and Nadal kept up the pace, breaking to love in game three with a fizzing forehand return and refusing to give the American a way back into the match.
Nadal finally secured a place in round two after exactly four hours and one minute but only after Isner had made him work for every point in the final game, and the American received a standing ovation from the Parisian crowd as he made his way off court.
"It was like a penalty shoot-out," A relieved Nadal said. "Isner's serve is almost unstoppable at the moment. In the tie-break you play under pressure all the time.
"It was a very, very tough opponent for me. I want to congratulate him for a fantastic match and wish him all the best for the rest of the season.
"It's always a very, very close match against John because you play under pressure all the time and at moments in the tie-breaks I didn't play very well, I was too nervous."
Isner was left a little shocked, having come so close to causing a huge upset on Court Philippe Chatrier on the third day at Roland Garros.
"I haven't seen tennis like that ever. That's why he's number one in the world and one of the greatest players ever," the 26-year-old said.
"I mean, that 30-all point in the last game, I needed oxygen after that. I almost collapsed. My legs were dead."