's-Hertogenbosch, The Netherlands (Sports Network) - Former world No. 1 star Kim Clijsters beat former French Open champion Francesca Schiavone in a quarterfinal showdown Thursday at the $220,000 UNICEF Open, a final Wimbledon tune-up.

The Belgian Clijsters bested her fellow non-seed Schiavone 6-3, 7-6 (9-7) on a rainy Day 5 on the grass courts at Autotron Rosmalen.

The four-time Grand Slam champion Clijsters captured this Dutch event in 2003 and was the runner-up in 2001. She's playing her first tennis in three months this week after being sidelined with a hip injury.

Clijsters' semifinal opponent on Friday will be Poland's Urszula Radwanska, who got past Swede Sofia Arvidsson in 6-2, 7-6 (7-3) fashion. The qualifier Radwanska is the younger sister of current world No. 3 star Agnieszka Radwanska.

One other quarterfinal result saw eighth-seeded former top-10 Russian Nadia Petrova paste third-seeded diminutive Slovak Dominika Cibulkova 6-2, 6-0 in exactly one hour.

Petrova awaits the winner between sixth-seeded and defending Den Bosch champion Roberta Vinci and Belgian Kirsten Flipkens, who was leading her Italian counterpart 6-4, 5-4 when play was called on Thursday. The qualifier Flipkens stunned top-seeded Sam Stosur here on Monday.

Vinci beat Aussie Jelena Dokic in last year's UNICEF finale.

The 2012 champion here will collect $37,000.