Vienna, Austria (Sports Network) - Top seeds Juan Martin del Potro and Janko Tipsarevic were among the quarterfinal winners Friday at the Erste Bank Open.

The top-seeded del Potro rolled to a 6-2, 6-2 win over Marinko Matosevic of Australia and will face Luxembourg's Gilles Muller in Saturday's semifinals. Muller advanced with a 6-3, 6-4 triumph over Italy's Paolo Lorenzi.

Tipsarevic, this week's second seed, was ahead 6-4, 4-2 when Slovenia's Aljaz Bedene retired with a left gluteus injury. The 28-year-old Serb will next meet Slovenian qualifier Grega Zemlja, who upended third-seeded German Tommy Haas, 6-4, 4-6, 6-2.

Del Potro, last year's Vienna runner-up to Jo-Wilfried Tsonga, is playing for the first time since the Davis Cup semifinals in September and is gunning for his third title of 2012. He won in Marseille and Estoril, while also losing in the Rotterdam final to Roger Federer. The Argentine star was also the bronze medalist at the London Olympics.

Muller has never won an ATP World Tour title and has been twice a runner-up. He lost to Andy Roddick in the Atlanta final back in July.

Tipsarevic, a 2009 Vienna semifinalist, won the Stuttgart crown in July and was a finalist the following week in Gstaad, while also finishing as the runner-up to start the year in Chennai.

Del Potro and Tipsarevic are still in contention for a spot in the season- ending ATP World Tour Finals. Just three places remain in the eight-man field. Del Potro is currently seventh, while Tipsarevic is ninth.

The newest Vienna champion will pocket $113,795.

The Sports Network