Alexander Zverev has yet again showcased his new-found grand slam grit to advance to his maiden major quarter-final with a steely fourth-round French Open win over Karen Khachanov.

For the third straight match, the German second seed fought back from two sets to one down before finally prevailing after almost three-and-a-half hours of enthralling tennis on Sunday.

Not even blisters on his toes or a warning for courtside coaching could deny the 21-year-old his first-time place in the last eight, after 11 previous grand slam attempts.

“I’m very happy about being in the quarter-finals here,” Zverev said.

“Going the hard way, going the long distance every single time and showing myself, showing everybody that I can play for as long as I need to.”

Zverev had also survived successive five-setters, including a match point against Damir Dzumhur, in his previous two outings.

How match he has in reserve for Austrian seventh seed Dominic Thiem next remains to be seen.

“I’m young, so I might as well stay on court and practice a little bit … It’s the best, a five-set match,” Zverev said.

“The draw doesn’t get any easier and I have to see how it goes in the next few days.”

A semi-finalist the past two years and the last man to bring down Rafael Nadal on clay, Thiem is again through to the last eight following a 6-2 6-0 5-7 6-4 triumph over Japan’s Kei Nishikori.

“I love these conditions; it was the first time for me on Court Philippe Chatrier not playing against Rafa so I could enjoy the court,” Thiem said.

“The first two sets were amazing but then he raised his level and it was 50-50.

“In the end, it was very close and I was a bit nervous in the end as it is always hard to serve to reach the quarter-finals of the French Open.”