PARIS, France (AFP) — Novak Djokovic was “hoping for the best” Thursday that his troublesome right knee won’t derail his dreams of finally winning Olympic gold.

Djokovic aggravated the knee, which required surgery in June, during his 6-3, 7-6 (7/3) win over Stefanos Tsitsipas in the quarter-finals on Thursday at Roland Garros.

The 37-year-old needed on-court treatment and a pain-killer after slipping on the baseline of Court Philippe Chatrier and hobbling gingerly around the arena.

He recovered from 0-4 and then 2-5 down, saving three set points in the ninth game, before racing away with the tie-break.

The Serbian faces Italy’s Lorenzo Musetti on Friday in the Last Four.

“I’m concerned about the state of the knee. I cannot give you exact information because I don’t have it. I have to go and examine the knee with medical staff and then let’s see,” Djokovic said.

“I’m playing at 7 p.m. tomorrow, which gives me slightly more time. But I’m hoping I can be ready and be optimistic. I have to be.”

He added: “The anti-inflammatory helped. But that effect is going to fade away, so I’ll probably have a more realistic picture tomorrow and then hope for the best.”