American Lisa Raymond scored a stunning three-set victory over world number one Martina Hingis last night and advanced to the semi-finals of the WTA Tour event in Zurich.

Raymond won 4-6, 6-2, 7-5 in a thriller to stun top-seeded Hingis, who had won both their previous meetings in straight sets. Hingis (17), who made her professional debut in this event four years ago, has lost only three previous matches this year - to Iva Majoli, Lindsay Davenport and Amanda Coetzer.

She raced to an early 3-0 lead and even though Raymond came back to 2-3 and played impressively in spurts, Hingis easily took the first set.

Raymond broke for a 4-2 lead in the second set, held for 5-2 by punishing anything Hingis hit short and then broke her again for the set.

The American broke Hingis again to lead 3-1 in the final set but the Swiss player broke straight back - with the aid of a double fault - and held for 3-3.

Raymond edged 4-3 in front with her seventh ace, then 5-4 with the aid of an over-rule by the umpire and then 6-5.

Hingis, trailing 0-40, saved the first match point with a steady volley but then netted a backhand to give the win to Raymond. The American, ranked 19th in the world, scored her fourth win over a top 10 player in the past two weeks.

Unseeded Raymond will now meet French player Nathalie Tauziat, who celebrated her 30th birthday with a 4-6, 6-1, 7-5 win over Sabine Appelmans of Belgium.

Second-seed Jana Novotna of the Czech Republic defeated compatriot Sandra Kleinova of 6-2, 76 (7/1) on her ninth match point and will face fourth-seed Davenport, who won an all-American clash 6-0, 6-4 against teenage prodigy Venus Williams, in the other semi-final.