Third seed Milos Raonic and US Open finalist Kei Nishikori will meet in a Japan Open final for the second time in three years on Sunday.
Canadian Raonic, seeded third, dominated Gilles Simon of France 6-1, 6-4 on Saturday to reach his third consecutive final in the capital. Nishikori mounted a comeback as he overhauled Germany's Benjamin Becker 4-6, 6-0, 7-6 (7/2).
The 24-year-old was treated for lower back pain during his Friday quarter-final but has soldiered on to the delight of daily sellout crowds at the 10,000 capacity Ariake Colosseum.
Nishikori powered back after losing the first set against Becker, sweeping the second to love and winning a tiebreaker to prevail after losing a 3-1 break in the final set.
Raonic and Nishikori are both contenders in the battle to secure places for next month's eight-man ATP World Tour Finals in London, with Nishikori standing provisional sixth and Raonic on eighth.
The Canadian lost to Nishikori here two years ago and was beaten a year ago for the title by Argentine Juan Martin del Potro.
Raonic finished off Simon with 11 aces to bring his total for the season past 900.
"I believe it's the best I have played all week," said the Canadian. "I executed well and I had a clear vision of what I need to do, so I was making the right shot selections.
"Gilles can get into a very comfortable rhythm from the baseline, so it was important to break him down, be aggressive and come forward to make him feel pressure."
Nishikori stands 3-1 against Raonic, beating his rival in Madrid and the US Open this season while losing to the Canadian at Wimbledon.
Raonic is looking forward to the challenge of facing the on-form Asian player.
"Against Kei, it is something to look forward to. A lot of people here want it (victory).
"I have to execute well and serve well, focusing on myself... It's something to look forward to and I want to reverse the result in the final here over the past two years."
Raonic needed just 71 minutes to advance, breezing through the opening set against the 37th-ranked Simon in just over half an hour.
But he then had to maintain his concentration for a further 30 minutes while the roof of the venue was closed because of drizzle.
The Canadian came out strong in the second set, breaking for 3-2 from a Simon double-fault, and then dominated to the end as he advanced on his second match point.
- Nishikori under pressure -
Raonic, winner of the Washington event in August, owns a 32-13 record this season.
Nishikori is feeling the physical toll from two weeks of intense tennis after winning the Kuala Lumpur tournament last week in the wake of his historic New York grand slam performance as the first Asian man to get to the title match at a major.
"It's not the best situation, but my back is fine this week. It was a tough win. He started well and I had to really fight to recover.
"Now there is another difficult match coming up. I'll have to try and recover so I can play my best to try and beat Milos."