PARIS — The French Open quarterfinal long believed to be automatic was the last one to be confirmed Monday night.

But there was no altering this collision course. Rafael Nadal, the nine-time French Open champion, will indeed face top-ranked Novak Djokovic on Wednesday.

That heavyweight bout — a final of sorts before the final — is scheduled to be played on Nadal’s 29th birthday, and he presumably will need to be at or near his best to keep it a festive occasion.

“Novak today is the best player in the world,” Nadal said. “He’s coming in here without losing almost any matches this season. To have any chance against him, I know I have to play my real best tennis, and that’s what I’m looking forward to.”

Djokovic continued his march through the draw Monday, finishing off Richard Gasquet, the No. 20 seed from France, 6-1, 6-2, 6-3. It did not take long for Nadal’s name to come up as Djokovic spoke in French with Fabrice Santoro in an on-court interview.

“Yes, yes, we are waiting for this match,” Djokovic said. “Of course, it’s the biggest challenge I can have on clay. He’s lost one match in his whole career here on this court. So it will be a beautiful match, I hope.”

Unlike Djokovic, Nadal has lost a set here this year. He was dominant for the first two sets against the rising young American Jack Sock on Monday, covering the court and generating angles and surprise as usual. But Sock, who has a wicked forehand of his own, eventually made it more complicated, breaking Nadal when the Spaniard served for the match at 5-4 in the third set.

The powerful Sock, a 22-year-old born in Nebraska and raised there and in Kansas, went on to force a fourth set, which Nadal eventually won to complete a 6-3, 6-1, 5-7, 6-2 victory.

“I think he has a very good future,” Nadal said.

Nadal is now 70-1 at the French Open and has never lost a match on the Suzanne Lenglen court, the tournament’s secondary showcase, which is where he and Sock traded topspin and quite a few drop shots.

But Nadal has had his most difficult season on clay this year, losing five matches on his favorite surface. That is more defeats than he had on clay from 2006 to 2010.