Dellacqua downs Stosur in Birmingham

Casey Dellacqua (pic) beat Sam Stosur to reach the quarter-finals of the WTA event in Birmingham.

Casey Dellacqua has upstaged higher-ranked compatriot Samantha Stosur to reach the quarter-finals of the WTA event in Birmingham.

Dellacqua contributed to Stosur's woes on grass, fighting back from a set down to send the tournament's second seed packing 2-6 6-2 6-2 on Thursday.

World No.43 Dellacqua will next face Japanese veteran Kamiko Date-Krumm, who thrashed Slovakian seventh seed Daniela Hantuchova 6-4 6-0.

The 29-year-old West Australian was ranked outside the world's top 200 last September as she struggled in her comeback from injuries.

However she return to the top 50 for the first time since 2008 last month and is inching back towards her career high of 39.

Dellacqua and Australia's top-ranked player Stosur had not played each other for more than a decade, but Dellacqua had won both of their previous encounters.

World No.17 Stosur, who lost to eventual champion Maria Sharapova in the last 16 at last month's French Open, was dominant in the first set but was blasted off the court as Dellacqua stepped up her aggression.

Stosur will now turn her attention to next week's event in Eastbourne, a final warm-up for Wimbledon.

Grass is Stosur's least-favoured surface and she equalled her best effort by reaching the third round of the grass court grand slam last year.

Elsewhere top seeded Ana Ivanovic of Serbia enjoyed an easy day, loosing just two games against American Lauren Davis to win 6-1 6-1.

Third seed Sloane Stephens had a much tougher time against fellow American Alison Riske but finished strongly to win 7-6 (7-4) 2-6 6-1.

It was a similar story for fourth seed Kirsten Flipkens of Belgium, a semi-finalist at Wimbledon last year, who came from a break down in the second set to defeat Canada's Aleksandra Wozniak 1-6 7-5 6-4.

The world number 25 now faces Barbora Zahlavova Stycova of the Czech Republic for a place in the last four.

Finally, fellow Czech Klara Koukalova reached the quarter-finals along with ninth seed Zhang Shuai of China.