Canada's Milos Raonic advanced to the semifinals of the Japan Open with his 40th victory of the season.

Raonic, seeded third, cruised past Slovakia's Lukas Lacko 6-3, 6-3 in just over an hour Friday.

The 22-year-old from Thornhill, Ont., once again used a dominant serve to beat his opponent, with 11 aces to only two for Lacko.

Raonic said taking the early lead was key following an overnight change in the weather.

"I felt I started really well, right from the beginning which allowed me to get into the match and continue from there," said Raonic.

'I felt like I dealt with the conditions well today. Confidence is a big part of it and helps you in those adjustments to the difference in conditions.'- Canadian tennis star Milos Raonic

The quarter-final was played under the closed roof of the Ariake Coliseum after to a cold front moved in bringing drizzle and chilly temperatures.

"I felt like I dealt with the conditions well today," said Raonic. "Confidence is a big part of it and helps you in those adjustments to the difference in conditions.

"Despite the weather changes from hot and humid to cold and not so humid the court has remained relatively the same — fast," he added. "But I just felt that I was aggressive through the match and that paid early dividends."

Raonic will next face Croatian Ivan Dodig, a winner over Finland's Jarkko Nieminen 6-2, 7-6 (3). Raonic has a 2-1 record against Dodig, having lost a second-round match last June on grass at Eastbourne and a Barcelona win in 2011.

Serving key

A win over Dodig would mark Raonic's return to the Tokyo final where he lost a year ago to Kei Nishikori.

"It will be another tough match against Ivan," said Raonic. "I've never beaten him and would like to. But I have to play at my best and keep doing what's been working so far this week. I'll have to keep up my serving if I want to have any chance to go farther."

Raonic, ranked 11th in the world, is coming off a title at the Thailand Open on Sunday and improved his season record to 40-17. He's trying to earn one of the last spots in the World Tour Finals in London next month.

Against Lacko, Raonic never faced a break point from his 81st-ranked opponent. The loss to Raonic was Lacko's 14th straight against a top-20 opponent.

Raonic, who stands 5-0 in quarter-finals this year, has not lost a set this week. He took early control against Lacko with two breaks to earn the first set in 25 minutes.

He went up a quick break in the second for a 2-0 advantage, and later closed his match with a service winner.

Sixth-seeded Nicolas Almagro of Spain upset fourth-seeded Nishikori 7-6 (2), 5-7, 6-3 to ensure there will be no repeat of
last year's final.

Meanwhile, top-seeded Juan Martin del Potro overcame Alexandr Dolgopolov of Ukraine 4-6, 6-4, 6-2 to reach the semifinals. Del Potro broke Dolgopolov twice in the second set and again to go up 3-1 in the third set at Ariake Colosseum. He closed out the match with another break when Dolgopolov's return was long.

The Argentine will face sixth-seeded Nicolas Almagro of Spain in the semis on Saturday. Almagro beat local favourite and defending champion Kei Nishikori 7-6 (2), 5-7, 6-3.