Top seed, Stan Wawrinka, would face unseeded Frenchman, Benoit Paire, in the final of the Japan Open in Tokyo.
French Open Champion, Wawrinka served strongly to beat Gilles Muller of Luxembourg 6-4 7-6 to reach his fourth final of the year.
Paire upset home favourite, Kei Nishikori, 1-6 6-4 6-2, to reach his first ATP Tour 500 final.
Nishikori came into the tournament as defending champion and looked set for successive titles, as he coasted through the first set.
Paire needed a medical timeout to reinforce strapping on his ankle, and the patch-up helped as he found a second win against an increasingly-nervous second seed.
The 26-year-old now has the chance to add to a Maiden Tour title won in Bastad earlier in 2015.