Kei Nishikori became the first Japanese tennis player to reach the final of the Monte-Carlo Masters in its 121-year history, after rallying to beat world No. 4 Alexander Zverev on Saturday.

Nishikori, currently 36th, battled out his fourth three-set victory in five matches this week, taking down the No. 3-seeded German and Monaco resident 3-6, 6-3, 6-4 in 2 hours, 12 minutes to set up a final with 10-time Monte-Carlo champion Rafael Nadal of Spain.

"I was able to reach a masters final again, and I'm really happy to be able to face Rafa (Nadal) in the final."

The former world No. 4 gave up the first set after double faulting on a 3-3 game point, allowing Zverev to capitalize on three straight errors and a long forehand.

(Getty/Kyodo)

Zverev came back from an early deficit in the second set, but Nishikori gained the upper hand when the German's service game broke and a mishandled forehand sent the match into a decider.

At 3-3 in the final set, Zverev sliced a deep return wide to give up the 10-minute seventh game and the Japanese hung on for the win.

"The third set was a test of mental strength. It was extremely difficult," Nishikori said.

The 21-year-old Zverev, who had won their only other meeting, was coming off a grueling 2:37 semifinal victory over France's Richard Gasquet.

"It was a good match. My serve wasn't there today. That's why I had to play a lot of long rallies," Zverev said. "Yesterday, obviously, the match was very tough physically. I was also very tired."

In pursuit of his first masters championship, Nishikori beat Tomas Berdych, Daniil Medvedev, Andreas Seppi, and Marin Cilic en route to his fourth ATP World Tour Masters 1000 final.

He has only beaten the world No. 1 Nadal twice in 11 encounters -- the last time two years ago to take the bronze medal at the Rio Olympics.

"(Nadal) has been playing very solid this week. On clay he's the king," Nishikori said. "I hope I can find a way to beat him."