Stan Wawrinka remained on course to capture the 11th title of his career Friday by reaching the Rakuten Japan Open Tennis Championships semi-finals, where he will meet Gilles Muller. The pair has played two times earlier this year, with Wawrinka winning their Chennai and Rotterdam encounters.

Top seed Wawrinka, who has three titles to his name this year, outclassed qualifier Austin Krajicek, currently No. 124 in the Emirates ATP Rankings, 6-3, 6-4 in 59 minutes on a hot day in Tokyo. He is now 46-13 on the year, which includes titles at Chennai (d. Bedene), Rotterdam (d. Berdych) and Roland Garros (d. Djokovic).

Wawrinka, competing in the Tokyo quarter-finals for the third time, was solid on serve for the majority of the 28-minute first set, which saw him break Krajicek to love in the sixth game. Having dropped four points in his first four service games, Wawrinka saved one break point at 5-3. Krajicek became more competitive in the second set, but Wawrinka raised his game to break for a 3-2 lead.

The Swiss has already qualified alongside Novak Djokovic, Andy Murray and Roger Federer for next month’s Barclays ATP World Tour Finals, but one player hoping to improve his chances of securing one of the four remaining spots at The O2 in London was beaten in the first match of the day.

Gilles Simon, who is currently No. 14 in the Emirates ATP Race To London, came unstuck against Muller, enjoying a career-best year. The 32 year old became the first player to reach the semi-finals after he struck eight aces and lost just six of his first service points in a 6-3, 6-4 over one hour and 36 minutes.

Simon came through a 15-point fourth game, but was powerless at 3-4 when Muller broke en route to winning the 46-minute opener. The World No. 43 opened up a 5-2 lead in the second set, courtesy of service breaks in the third and seventh games. However, at 5-3, he withstood five break points but could not convert his first match point opportunity and was broken. Simon’s rally was too late, as Muller closed out his 31st win of the season.

Muller also reached the semi-finals at Sydney (l. to Troicki), ‘s-Hertogenbosch (l. to Goffin) and Atlanta (l. to Baghdatis) this year. He’ll now look to reach his first ATP World Tour final since July 2013 at Atlanta (l. to Roddick).