The 28-year-old Frenchman hit his head with his free hand even before an ill-advised drop shot fell woefully short, a rare moment of confusion in a remarkable run of consistently good decisions. At 30-all -- a perilous position in the context of this match -- Isner rifled a forehand pass. The American pumped his fist with a surprising vigor and returned to the baseline with his fifth match point.
When a lovely backhand pass sailed past Mahut, Isner -- all 6-foot-9 of him -- tumbled to the dry grass on Court No. 18, and the longest match in the history of tennis was suddenly, oddly, over.
Savor this score, for you will probably never see its kind again: 6-4, 3-6, 6-7 (7), 7-6 (3), 70-68.
Over three days that were not once visited by rain, in a match that consumed 11 hours, 5 minutes -- a cartoonish number that somehow fails to capture this raw, brutal struggle that consisted of 183 games -- Isner was just a few, well-timed shots better than Mahut in the end.
The fifth set ran 8 hours, 11 minutes -- 98 minutes more than the longest match on record. Thursday's portion of the proceedings was a relatively modest slice of 65 minutes, and Isner edged Mahut 11 games to nine. For the record, Tuesday's court time was 2 hours, 54 minutes, and Wednesday ran a memorable 7 hours, 6 minutes.
According to ESPN Stats & Information, there were no fewer than 380 towel-offs during the match -- another, perhaps more subjective, record.
"When you come out and play a match like this in an atmosphere like this, you don't feel tired," Isner said in an on-the-court interview. "The guy [Mahut] is an absolute warrior."
Said Mahut, "He just served unbelievable."
Actually, they both did. Isner stroked a record 112 aces, while Mahut's 103 aces were 25 better than the previous record.
Technically, Mahut held a surprising edge in total points, 502 to 478. Appropriately, their net of winners to unforced errors was an identical plus-184.
After Isner gently hugged Mahut at the net, there was a postmatch presentation worthy of a championship final. The players were presented gifts by 1969 Wimbledon champion Anne White and former British No. 1 Tim Henman.
Afterward, the players tried to describe the mental and physical toll that was exacted.
"I was completely delirious," Isner said of the Wednesday suspension. "I wanted to keep on playing yesterday, but I don't know why. I wanted a final verdict, win or lose. But it wasn't to be."
He drank a recovery shake and tried to squeeze down a plate of pasta. He ate as much as possible and took an ice bath to bring back his arm. Andy Roddick left the site and came back with takeout food for Isner and his coach, Craig Boynton.
"Honestly, when I left the match here, I really thought it was a dream," Isner said. "I didn't think that type of match was possible. I was expecting to wake up. I only slept for four hours [from about 12:30 a.m. to 4:30 a.m.]. I talked to Nic, and he said he slept three. We're both kind of running on fumes right now."
What was he thinking Wednesday as the match progressed?
"I wasn't really thinking," Isner said. "I was trying to hit a serve and hit a forehand winner. Going out there today, I had a feeling it wouldn't be anything like yesterday."
Why, ultimately, did it take so long?
"I can't explain that," Isner said. "Obvious[ly] both players served really well. Even in that case, you can't even imagine it going past 20-all. I was slapping my forehand as hard as I could, and it kept going in. I don't know I guess it was just meant to be. In a way, I'm glad I was part of that match.
"It's great, something Nic and I will share forever, really. I never said five words to the guy prior to the match. When I see him in the locker room at tournaments, we can share this."
Isner will try to regroup; his second-round opponent is Thiemo de Bakker of the Netherlands, who beat Santiago Giraldo by the relatively low score of 16-14 in the fifth. Isner also confirmed, incredibly, that he is still committed to playing doubles with partner Sam Querrey.
Greg Garber is a senior writer for ESPN.com.