It is the first time Alexander Zverev has reached the quarter-finals of a Grand Slam and he will face Austrian seventh seed Dominic Thiem
Second seed Alexander Zverev survived a third successive five-setter to see off big-hitting Russian Karen Khachanov 4-6 7-6(4) 2-6 6-3 6-3 in the French Open fourth round on Sunday.
The German, fired up by a code violation for being coached from the stands by his father, stormed into the lead in the fourth set before securing victory in 3-1/2 hours on Court Suzanne Lenglen.
"I'm young, so I might as well stay on court and practise a little bit," Zverev said courtside. "It's the best, a five-set match.
It is the first time Zverev has reached the quarter-finals of a Grand Slam and he will face Austrian seventh seed Dominic Thiem, who beat Japan's Kei Nishikori 6-2 6-0 5-7 6-4.
Nishikori took his only break point opportunity to claim the third set but Thiem, twice Roland Garros semi-finalist, regained control in the fourth.
Former champion Novak Djokovic never looked in trouble as he booked a 12th quarter-final appearance in Paris with a 6-3 6-4 6-2 win over Spanish veteran Fernando Verdasco.
U.S. Open runner-up Madison Keys advanced to the last eight without dropping a set, defeating Romania's Mihaela Buzarnescu 6-1 6-4.
Up next for Keys is Kazakh Yulia Putintseva, who upset 26th seed Czech Barbora Strycova 6-4 6-3.
Sloane Stephens sprinted past Estonian Anett Kontaveit 6-2 6-0 to set up a potential semi-final meeting with Keys, whom she beat in last year's U.S. Open final.
Play was suspended due to fading light, with Russian Daria Kasatkina leading 7-6(5) 3-3 against second-seeded Caroline Wozniacki.
Italian Marco Cecchinato, who had never won a Grand Slam match before this week, beat eighth-seeded Belgian David Goffin 7-5 4-6 6-0 6-3 to reach his first major quarter-final.
At world number 72, Cecchinato becomes the lowest-ranked man to reach the last eight in Paris since Latvian Ernests Gulbis (ranked 80) in 2008.
He will next face 2016 champion Novak Djokovic for a place in the final four.
"For me it is a dream," Cecchinato said. "It will be a pleasure to play against Novak."
Third-seed pair of Andreja Klepac and Maria Jose Martinez Sanchez survived a mid-match blip to beat Serena and Venus Williams 6-4 6-7(4) 6-0 in the women's doubles clash.
The Williams sisters have claimed 14 Grand Slam doubles titles together since winning the French Open title in 1999, but bowed out at the last-16 stage this year.
Kazakh Yulia Putintseva produced a clinical display to beat 26th seeded Czech Barbora Strycova 6-4 6-3 in exactly one hour and 30 minutes.
Putintseva matched her best Roland Garros performance by reaching the quarter-finals for the first time since 2016.