Carlos Alcaraz dug in to start his Japan Open title defence with a three-set win over Alex Michelsen.

Alcaraz triumphed in Tokyo last year, but the world number three was made to work for his victory on Thursday.

He eventually prevailed 7-6 (7-1) 4-6 6-1 in two hours and 3 minutes.

"I was unable to practise outside [because of the rain] until the warm-up this morning and I hadn't played any points outdoors for a long time, so it was quite different," said Alcaraz.

"It was a different feeling. I think the ball comes bigger. I think the court performs a little bit slower than the indoor courts for sure, so it was kind of freaky to adjust myself to that, to adjust my game.

"It was a little bit frustrating, not being able to play my game, my style, and play aggressive. It was quite difficult but I'm just really happy to accept and understand how I had to play, and to get the win at the end.

"It was really important to have this feeling for the next round, to know what I have to do for the next matches."

Alexander Zverev, meanwhile, kept up his fine form with a 7-6 (7-1) 6-4 defeat of Cameron Norrie at the China Open.

Back in ATP Tour action following his US Open triumph, Zverev claimed his ninth straight win over Norrie.

Zverev is hunting down the year-end world number one spot. He leads the Tour in 2026 for hard-court wins (28).

Nishikori calls it a day

While Alcaraz was the biggest name on court in Tokyo on Thursday, it was an emotional affair for Kei Nishikori.

There’s only one Kei Nishikori @keinishikori pic.twitter.com/bd5pKrvvp4

— ATP Tour (@atptour) October 1, 2026

In front of his home crowd, Nishikori played his final competitive match as he went down 6-4 6-4 to world number eight Frances Tiafoe.

The 36-year-old is now officially retired. He became the first Japanese man to reach a grand slam final when he played in the US Open showpiece against Marin Cilic in 2014.

Nishikori also claimed an Olympic bronze medal in 2016.

"Playing in Japan is always a special moment," Nishikori said. "I wish I could have put in a slightly more convincing performance. But I'm happy I kept fighting right to the end.

"I'm proud that I didn't give up and played right to the finish."

Nishikori bows out having won 452 Tour-level matches and 12 titles. He reached a further 15 finals.