John Isner of the US (left), France's Nicolas Mahut (2nd left), and chair umpire Mohamed Lahyani (2nd right), pose with the score board at the end of their match at the Wimbledon Tennis Championships on June 24. (AFP)

LONDON (AFP) – John Isner and Nicolas Mahut said they were absolutely exhausted by their epic duel but bound together for life after they played out the longest tennis match ever known.

Both were utterly lost for words as to why their unprecedented encounter had gone on for so long, except to say the will to win was never extinguished.

"I can't explain that," Isner, the American world number 19, said after the incredible record-shattering contest.

"Nothing like this, it won't happen again. Not even come close," he said, after finally beating Mahut 6-4, 3-6, 6-7 (7/9), 7-6 (7/3), 70-68.

"I guess it was just meant to be. In a way I'm kind of glad it happened, although I'm pretty tired.

"I didn't know what I was thinking out there, especially once the match got past 25-all. I wasn't really thinking."

Mahut was struggling to control his emotions as he reflected on the duel.

"This is just a match I will never forget. I hope the people who watched the match will think the same," the world number 148 said.

"At this moment, it's really painful.

"I just wanted to win. He was just better than me. Really painful to lose this kind of match."

Isner said he had no idea what was going on by the time the match was suspended due to bad light at 59-59 after seven hours on court Wednesday.

"I was completely delirious. I wanted to keep on playing, which I don't know why, because he was the fresher one. Even though it was dark and no-one could see, I wanted a final verdict, win or lose.

He said his compatriot Andy Roddick turned up in the locker room with armfuls of pizza, chicken and mashed potatoes to pump some carbohydrates back into him.

Isner only managed four hours' sleep; perhaps that made the difference, as Mahut only managed three.

"We were both kind of running on fumes," the American number two said.

"I was so tired out there. Couldn't focus. Didn't know what I was going through.

"In the back of my mind is, as I'm sure it was with him, 'I don't want to be on the losing side of this'.

"Not that I outwilled him. He gave it his all. I was just a little bit more fortunate than he was."

In the epic fifth set, Mahut had to serve to stay in the match an unprecedented 65 times.

"I was behind all the match," he said.

"I just try to win the game, just to win the point I was playing. That's it. Again and again, every time the same.

"He's a champion. He served unbelievable. Every time I was that close to breaking him, he just serves aces, aces, bomb. I could not do anything. I tried very hard, but he was just too good."

Mahut said there would be an affinity between the two for life, while Isner said their achievement was something they would "share forever".

Both accepted that they were now part of sporting history.

"I just want people to remember that we were just two big fighters, and one of them just won," Mahut said.

Isner said: "This one's obviously going to stick with me probably the rest of my life really. But I hope it doesn't define my career. I think I have what it takes to do some really big things in this game.

"So hopefully this won't be the thing that I'm most remembered about."