Canada's Milos Raonic advanced to the semi-finals of the Japan Open with his 40th victory of the season Friday.
Raonic, seeded third, cruised past Slovakia's Lukas Lacko 6-3, 6-3 in just over an hour.
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.
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, who defeated Finland's Jarkko Nieminen 6-2, 7-6 (3). Dodig has won two of the pair's three matches, including a second-round victory over Raonic last June on grass at Eastbourne and a Barcelona win in 2011.
A win over Dodig would mark a return for Raonic to the Tokyo final where he lost a year ago to Kei Nishikori.
"It will be another tough match against Ivan," said Raonic. "I'm focused on what I need to do for the next one."
Raonic, ranked 11th in the world, is coming off a win 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.
Raonic never faced a break point against the 81st-ranked Lacko. 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.
Raonic went up a quick break in the second for a 2-0 advantage, and later closed his match with a service winner.
Meanwhile, top-seeded Juan Martin del Potro overcame Alexandr Dolgopolov of Ukraine 4-6, 6-4, 6-2 to reach the semi-finals. 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.
— With files from The Associated Press