TOKYO: Unseeded Frenchman Benoit Paire will take on Stan Wawrinka in the Japan Open final after storming back from a set down to upset home favourite Kei Nishikori in the semi-finals on Saturday.

Paire, competing in his first ATP Tour 500 semi-final, looked out of sorts in the opening set but found his range following a medical timeout in the second to re-tape his ankle.

The bearded 26-year-old Frenchman grew in confidence with some strong returns and big serves to secure a 1-6 6-4 6-2 win over the double defending champion, who became more tentative as the match wore on.

Paire won his first ATP Tour title on the clay at Bastad in July and will go in search of his second against French Open champion Wawrinka, who served strongly in taking out Gilles Muller of Luxembourg.

The Swiss top seed coming through 6-4 7-6(5) to reach his fourth final of the year.

The opening set went with serve before Wawrinka broke in the seventh game and went on to close it out, dropping just four points on serve in the set.

Muller, who will break back in to the top 40 after his strong run in Japan, found a way to pressure Wawrinka in the second set by rushing the Swiss and breaking serve but failed to capitalise as he lost his own.

The set went to a tiebreak with Muller putting a backhand volley wide to hand Wawrinka the win on his first match point.