Alexander Zverev described the code violation he received during a five-set French Open thriller with Karen Khachanov as "ridiculous" and "nonsense".

The second seed reached his first grand slam quarter-final by fighting back to win 4-6 7-6 (7-4) 2-6 6-3 6-3 on Court Suzanne-Lenglen on Sunday.

Zverev has come through three consecutive matches that went the distance to break new ground at a major.

But the German was not impressed with being deemed to have received coaching during the fourth set in a tense battle.

The world number three said: "I thought it was a bit ridiculous, to be honest, because I was on the other side of the court. I was breathing and looking towards the fans, and I hear, in the back of my head, I hear 'code violation'.

"I thought he did something. I turned around and he was, like, it's for me. Well, I'm on the other side of the court.

"I don't think my dad or anybody in my box can show me or would say something that I would hear inside that big stadium. So for me it was nonsense."

Zverev said his progress in Paris has not been an education, but he is relishing proving that he has the staying power to come through such gruelling tests.

Asked what he has learned from such long duels in Paris this week, he said: "Nothing. I know who I am. It's not about learning anymore.

"It's about trying to find a way and trying to win. That's what I am able to do in the last few matches, and I'm very happy about that.

"I'm very happy about being in the quarter-finals here with going the hard way, going the long distance every single time and, you know, showing myself, showing everybody that I can play for as long as I need to."