Tokyo - Top seed Marin Cilic crushed local favourite Yasutaka Uchiyama 6-3, 6-4 on Wednesday to reach the Japan Open quarter-finals.
The towering Croatian, runner-up to Roger Federer at this year's Wimbledon and a former US Open champion, needed just over an hour to complete the rout in Tokyo.
Cilic, the current world number five and a semi-finalist in Japan last season, hit 14 aces and dropped only four of 34 points on his first serve as he advanced to play American Ryan Harrison in the last eight.
Harrison upset fifth seed Kevin Anderson of South Africa -- who reached last month's US Open final, where he was beaten by Rafa Nadal -- 6-3, 1-6, 7-6 in a see-saw match.
Elsewhere Argentina's Diego Schwartzman advanced, the eighth seed thumping Bernard Tomic of Australia 6-3, 6-1, while Frenchman Adrian Mannarino overpowered Czech Jiri Vesely 6-3, 6-2.
In first-round matches, fourth seed David Goffin, instrumental in Belgium's run to next month's Davis Cup final, beat Spain's Feliciano Lopez 7-5, 6-1.
Goffin ended a wretched run of six defeats in his previous six finals by capturing the Shenzhen Open earlier this month.
Meanwhile, Ukrainian Oleksandr Dolgopolov thrashed Russia's Daniil Medvedev 6-1, 6-2 in another first-round match.
On Thursday, third seed Milos Raonic of Canada continues his return from wrist surgery at the hardcourt event, whose previous champions include tennis greats John McEnroe, Pete Sampras, Roger Federer and Nadal.