Tokyo: Top-seeded Juan Martin del Potro moved into Japan Open quarterfinals with a comfortable 6-2, 6-2 win over fellow Argentine Carlos Berlocq on Wednesday.
Del Potro broke Berlocq's serve twice in the second set, and lost only eight points on serve under the roof, closed by rain. After Tuesday's three-set victory over Marcos Baghdatis, del Potro said it was good to find his rhythm.
"I played a lot better than yesterday," del Potro said. "I served well, my forehand was strong and I was able to break his serve and be aggressive. I had control of the match all the time which was important to me."
Del Potro, who is seeking his third title of the season following victories in Rotterdam and Washington, will next play Alexandr Dolgopolov of Ukraine, who defeated eighth-seeded Janko Tipsarevic of Serbia 6-3, 7-6 (2).
In the day's only upset, Ivan Dodig of Croatia ousted second-seeded Jo-Wilfried Tsonga 6-4, 7-6 (5).
Matching 2009 champion Tsonga with nine aces, Dodig saved all three break points he faced.
Dodig will attempt to earn a place in his third semifinal of 2013 against Jarkko Nieminen of Finalnd, who beat Michal Przysiezny of Poland 6-7 (4), 6-4, 6-2.
In other matches, third-seeded Milos Raonic of Canada advanced to the second round with a 6-4, 7-6 (0) win over wild card Go Soeda of Japan in the opening match on Center Court.
Raonic, coming off a win at the Thailand Open on Sunday, dominated Soeda with his serve, hitting 24 aces.
"I served really well," Raonic said. "It was a bit earlier in the day than what I'm used to but I played well on the important points and did what I needed to do."
Raonic lost in the final last year to local favorite Kei Nishikori, who will face Feliciano Lopez of Spain in the second round on Thursday.
The fourth-seeded Nishikori is on the verge of becoming the first Japanese player to break into the top 10 and is bidding to win his second title of the season.