Tokyo - Top-seeded Juan Martin del Potro moved into Japan Open quarter-finals with a comfortable 6-2, 6-2 win on Wednesday of fellow Argentine Carlos Berlocq.
Del Potro broke Berlocq's serve twice in the second set and closed out the match in 1 hour, 6 minutes.
Del Potro was a late addition to the tournament after Andy Murray, the 2011 champion, withdrew due to a back injury. Del Potro is seeking his third title of the season here, following victories in Rotterdam and Washington.
In other matches, third-seeded Milos Raonic of Canada advanced to the second round with a 6-4, 7-6 (0) win over Go Soeda of Japan.
Raonic, coming off a win at the Thailand Open on Sunday, dominated Soeda with his serve, hitting 24 aces against the Japanese wildcard.
Results from the ATP Japan Open in Tokyo on Wednesday (x denotes seeding, *new result):
Milos Raonic (CAN x3) bt Go Soeda (JPN) 6-4, 7-6 (7-0)
*Alexandr Dolgopolov (UKR) bt Janko Tipsarevic (SRB x8) 6-3, 7-6 (7-2)
*Jarkko Nieminen (FIN) bt Michal Przysiezny (POL) 6-7 (4-7), 6-4, 6-2
Juan Martin del Potro (ARG x1) bt Carlos Berlocq (ARG) 6-2, 6-2
Ivan Dodig (CRO) bt Jo-Wilfried Tsonga (FRA x2) 6-4, 7-6 (7-5)
Jeremy Chardy (FRA) bt Marco Chiudinelli (SUI) 7-6 (7-2), 3-6, 7-6 (8-6)