Stefanos Tsitsipas survived an astonishing second-set fightback from Alexander Zverev to reach the Monte Carlo Masters quarter-finals with a 7-5, 7-6 (7-3) victory on Thursday.
Former two-time tournament winner Tsitsipas was a set and 5-0 up, and held two match points in the sixth game when he suffered a major collapse.
Olympic champion Zverev roared back to 5-5 before his comeback ended after 2 hours six minutes in the tie-break.
"I would call it an adventure of a lifetime," the ATP website quoted Tsitsipas as saying.
"Something I am not faced with every single day and momentum shifted dramatically at some points. It went one way and then it went completely the other way again. I don't even know, I am trying to figure out right now what happened.
"It is a big win. I am grateful I was able to play the way I did today. It took a lot of mental strength throughout the entire match. Today's match was a great assessment to how much I can fight in tough moments."
Twelveth seed Tsitsipas, who lifted the trophy in 2021 and 2022, improved his record against Zverev to 10-5 and on Friday meets Karen Khachanov.