Unseeded American Tommy Paul came from a set and a break of serve down on Wednesday night to beat the second seed Rafael Nadal.
Paul advanced to the third round 3-6, 7-6, 6-1 after just over two and a half hours on centre court at the Accor Arena in Bercy, south-eastern Paris.
"I'm happy I played well," said the 25-year-old in his on-court interview.
"I came in not expecting much support so I was surprised to get some cheers," he added. "A big thank you to those who supported me."
Nadal won the first meeting between the pair at the Mexico Open in Acapulco earlier this year.
And the Spanish veteran appeared on track to repeat the feat when he claimed the first set despite no competitive tennis since September when he played in the doubles with Roger Federer for Team Europe at the Laver Cup in London.
Fight
However, Paul - who also featured at the tournament for Team World - dug in, recovered from the early loss of his service to take the set into a tiebreaker.
Nadal started with a double fault and never recovered the deficit. He was quickly under the cosh in the decider and Paul held his nerve to claim a famous win.
"I had my chance," said Nadal. "I was a set up with a break but I played terrible service game there.
"I didn't deserve the victory playing that bad in that key moment.
"Until then it was OK but on this surface especially, you cannot make mistakes with your serve."
On Thursday night, Paul will face a Spaniard for the third time in as many rounds when he takes on the 14th seed Pablo Carreno Busta for a place in the quarter-finals.
