Updated

Tokyo, Japan (SportsNetwork.com) - Top seed Juan Martin del Potro won his second straight match Wednesday at the Japan Open Tennis Championships, but second-seeded Jo-Wilfried was a second-round upset victim.

Del Potro followed up his shaky, three-set first-round win over Marcos Baghdatis from Tuesday with a 6-2, 6-2 rout of fellow Argentine Carlos Berlocq. The 2008 Tokyo runner-up is playing his first event since a stunning second-round loss to Lleyton Hewitt at the U.S. Open, and shook off the rust from Tuesday with a strong performance Wednesday that took just 66 minutes and featured four breaks of serve.

"I played better than yesterday, which was pleasing," said del Potro. "I hit my forehand really strong and I was confident, able to break serve many times."

Next up for del Potro will be Alexandr Dolgopolov of the Ukraine in Friday's quarterfinals. Dolgopolov advanced Wednesday with a 6-3, 7-6 (7-2) win over eighth-seeded Janko Tipsarevic of Serbia.

Croatia's Ivan Dodig pulled off the surprise of the day with a 6-4, 7-6 (7-5) win over Tsonga, the 2009 Tokyo champ. The Frenchman was playing just his second tournament after recovering from a knee injury suffered at Wimbledon. He was the runner-up in Metz eight days ago, falling to fellow Frenchman Gilles Simon in the final.

Dodig will next face Jarkko Nieminen, as the veteran Finn rallied for a 6-7 (4-7), 6-4, 6-2 win over Poland's Michal Przysiezny.

The first round was also completed Wednesday and third-seeded Milos Raonic came away with a 6-4, 7-6 (7-0) triumph over Japanese wild card Go Soeda. Raonic, fresh off his Bangkok crown from Sunday, will next take on Frenchman Jeremy Chardy, a 7-6 (7-2), 3-6, 7-6 (8-6) winner over Swiss qualifier Marco Chiudinelli.

In addition to the Raonic-Chardy match, Thursday's second-round action will also include defending champion Kei Nishikori against Spain's Feliciano Lopez and sixth-seeded Nicolas Almagro versus Argentina's Horacio Zeballos, as well as French qualifier Edouard Roger-Vasselin against Slovakian lucky loser Lukas Lacko.