Sofia, Bulgaria (SportsNetwork.com) - Australian Open runner-up Dominika Cibulkova notched a round-robin victory Tuesday at the $750,000 WTA Tournament of Champions.

The diminutive second seed from Slovakia swept past heavy Bulgarian crowd favorite Tsvetana Pironkova 6-3, 7-6 (8-6) on the indoor hardcourts at Armeets Arena.

Two other opening-day results saw third-seeded Italian Flavia Pennetta paste sixth-seeded Frenchwoman Alize Cornet 6-1, 6-2 and fifth-seeded Spaniard Carla Suarez Navarro upend fourth seed Andrea Petkovic of Germany 6-0, 6-4.

Cibulkova (1-0) heads up this week's Sredets Group, which also includes Petkovic (0-1), Suarez Navarro (1-0) and Pironkova (0-1). The four-woman Serdika Group features top-seeded Ekaterina Makarova, Pennetta (1-0), Cornet (0-1) and seventh-seeded Garbine Muguruza.

Wednesday's round-robin affairs will pit Makarova against Muguruza, Cibulkova versus Suarez Navarro and Petkovic against Pironkova.

This eight-player season-ending tournament is for players who have won one or more of the WTA International events during the year but did not qualify for the WTA Finals, which was staged last week in Singapore.

This six-year-old event will move to Zhuhai, China, next year after a three- year run in Sofia.

Simona Halep beat Samantha Stosur in last year's finale.