Having gone five sets in the first round against Italian qualifier Alessandro Giannessi, Nishikori needed to go to five again, thanks to Khachanov, a former quarter-finalist in Paris, who played aggressively and boldly throughout.
The Russian looked like he would go on to win when he took the third set but after a gruelling exchange of games at the start of the fourth set, all of which went to deuce, Nishikori levelled the match and it was then that his five-set record kicked in.
“Because everybody is telling me I have good records, sometimes I have to think that I have to keep building my record after going five sets,” he said, with a smile. “That's little bit giving me pleasure, too.
“I think fifth set, I'm really playing good tennis, more than any sets. Even though I'm tired, I think I'm playing better and more free, more aggressive, not being passive. Yeah, I think I do many good things, especially in the last set.”