Pouille beat Nadal in a five-set classic.
Lucas Pouille upset No. 4 seed Rafael Nadal in Sunday's U.S. Open fourth round, sending the Spaniard home by beating him 6-1, 2-6, 6-4, 3-6, 7-6(6) in just over four hours at Arthur Ashe Stadium.
Pouille, 22, will play compatriot Gael Monfils in the quarterfinals on Tuesday.
Nadal, the tournament's No. 4 seed, hadn't dropped a set in three matches entering his fourth-round affair with Pouille. But he was shaky to start Sunday's match as the No. 24–seeded Pouille rolled the two-time U.S. Open champion in the opening set.
Pouille never seemed rattled, even after Nadal mounted two comebacks. After Nadal won the fourth set 6-3, the two players battled for more than an hour in a back-and-forth fifth set, which ended in a tiebreaker.
After Pouille jumped out to a 6-3 lead in the tiebreaker, Nadal saved three match points, but Pouille won the next two points to clinch a spot in the quarterfinals.
At 6-6, Nadal hit a routine forehand into the net, giving Pouille a fourth match point. After Pouille clinched the match with a forehand winner to the deuce side, he collapsed to the ground.
"He's like every player. He feel the pressure as well," Pouille said. "Even if he's one of the best, he feel the pressure."
After the match, Nadal said he felt good physically and felt that he played a good match—but that Pouille was just a bit better.
"I need something else, I need something more that was not there today," Nadal said. "I going to keep working to try to find [it]."
Nadal later added: "When the opponent beat you, is not the time to find excuses mental or physical. Doesn't matter. The opponent was a little better than you. That's it."
Arthur Ashe Stadium grew raucous as the match moved into the fourth and fifth sets. By time the players entered into a fifth-set tiebreaker, it was defeaning.
"Sometimes I couldn't even hear myself when I was saying, 'allez, allez, allez,'" Pouille said.
Monfils, Pouille and Jo-Wilfried Tsonga all reached the quarterfinals, the first time since 1947 that three Frenchmen have reached the quarterfinals of a Grand Slam event.
This year's U.S. Open marks Pouille's second Grand Slam quarterfinal appearance after he made the quarterfinals at Wimbledon earlier this summer.
Nadal started with a wrist injury at the French Open, forcing him to withdraw mid-tournament and miss Wimbledon. Nadal, who last won a Slam at the 2014 French Open, failed to make the quarterfinal at a single Grand Slam event in a calendar year for the first time since 2004.
Nadal, 30, has won 14 Grand Slam titles over his career, including the 2010 and 2013 U.S. Opens.