Rafael Nadal will aim to reach a 14th French Open final on his 36th birthday on Friday - although it remains to be seen whether it could be his last.

But the Spaniard is yet to find a "solution" to his chronic foot injury.

"The last three months and a half, for me, the only thing that I can say is they haven't been easy," Nadal said.

"If we are not able to find an improvement or a small solution, then it's becoming super difficult for me. So that's it," added the world number five, whose encounter with Zverev is scheduled to start at 13:45 BST.

"It's not the moment to talk about [what happens after the French Open]. We are going to talk about that when my tournament finishes."

Nadal overcame defending champion and world number one Novak Djokovic in a thrilling four-set and four-hour encounter in Tuesday's night session.

His 110th win at Roland Garros leaves him two victories away from moving another title clear of 20-time major winners Djokovic and Roger Federer.

Despite winning the Australian Open in January after returning from the foot problem that he feared may end his career, it is clear the injury is still causing issues.

"I am just enjoying every day that I have the chance to be here, and without thinking much about what can happen in the future," Nadal said.

"Of course I'm going to keep fighting to find a solution, but for the moment, we haven't.

"I don't know what's going to happen after here."

Zverev eyes another shot at maiden Grand Slam

Nadal has won six of his nine matches against Zverev - and four of their previous five meetings on clay.

The 25-year-old German's wait for a maiden Grand Slam title continues but he did record his first victory over a top-10 opponent at a major with an impressive four-set win over talented Spanish teenager Carlos Alcaraz in the quarter-finals.

That display secured a second successive French Open semi-final for the 2020 US Open finalist - and victory against Nadal would set up his best chance yet of claiming a maiden Slam, against either Norwegian eighth seed Casper Ruud or Croatia's Marin Cilic.

"I'm not 20 or 21 years old anymore. I'm 25. I am at the stage where I want to win, I'm at the stage where I'm supposed to win," Zverev said.

"Yes, I have not beaten [Djokovic or Nadal] in majors, but I feel like I was very close," he added.

"I feel like I have had very difficult and tough matches against them. But there is a big difference between having a tough match and beating them. Still a major difference."

Ruud chases debut final against experienced Cilic

World number 23 Cilic, edged a captivating four-hour match against Russian seventh seed Andrey Rublev in a fifth-set tie-break to book his place in the final four at Roland Garros for the first time.

With that achievement, the experienced 33-year-old became the fifth active men's player, after current world number one Djokovic and former top-ranked players Nadal, Federer and Andy Murray, to reach the semi-finals of all four Grand Slams.

The 2014 US Open champion, who also reached finals at Wimbledon in 2017 and the Australian Open in 2018, meets a first-time major semi-finalist in Ruud - the first male Norwegian player to reach the last four at a Grand Slam.

Having ended unseeded 19-year-old Holger Rune's run in the previous round, Ruud has recorded the most ATP clay-court wins since the start of 2020 with an impressive 65.

"These are the matches that you dream about playing, and hopefully of course even the final if it's possible," said Ruud.

"I have to be really focused and bring my A-game in the semi-final. Marin has played great all week, and it's going to be another tough match."

Their semi-final will follow the Nadal-Zverev match on Court Philippe Chatrier.