With this victory, Rune, ranked 40th in the world, will become the first Dane to reach the quarter-finals of Roland Garros, where he will face Norway’s Kasper Ruud.
The former French Open junior champion, the 19-year-old is also the first Dane to reach the quarter-finals of any Grand Slam tournament since Jan Lashley in 1967, according to the ATP Tour.
“Now I have an incredible feeling,” Rune said in his on-court interview after the match on Monday. “I was so nervous at the end, but the audience was amazing for me throughout the match, the entire tournament.”
He won a close first set against last year’s finalist Tsitsipas just over an hour before the Greek equalized thanks to a service break at 4-3 in the second.
Rune regained the lead with a half-time break in the middle of the third set to take a 5–2 lead in the fourth to help close the win.
Along with Spaniard Carlos Alcaraz, Rune is only the second teenager to reach the final eight of the men’s singles draw at Roland Garros this year, marking the first time two male teenagers have reached the quarter-finals of a major since 1994.
It ends a stunning year for Rune, who scored his first win against a top-five player when he defeated Alexander Zverev at the Munich Open in April.
He will play Ruud on Wednesday after the 23-year-old defeated Poland’s Hubert Hurkacz 6-2, 6-3, 3-6, 6-3.
Meanwhile, Tsitsipas becomes the highest ranked player – and the first in the world’s top eight – to be eliminated from the men’s bracket at this year’s French Open.