Top seed Jennifer Capriati has tumbled out of the Porsche Grand Prix after a shock 7-6 (7/4) 4-6 4-6 defeat by fellow American Alexandra Stevenson in the second round.

Capriati had enjoyed a first-round bye, but she was not ready for her 21-year-old rival, who unleashed a series of crisp backhand winners.

"I don't think I played badly - but Alexandra came up with some incredible shots," said Capriati.

Stevenson, who also beat Capriati in January in the Sydney International, first came to prominence in 1999 when she reached the Wimbledon semi-finals.

"Against Jennifer you have to play physical tennis and I managed to do so," she said.

Stevenson will next meet either Austria's Barbara Schett or Slovak eighth seed Daniela Hantuchova for a place in the last four.

Second round results (prefix denotes seeding):
A Stevenson (US) bt 1-J Capriati (US) 7-6 (7/4) 4-6 4-6
2-L Davenport (US) bt A Smashnova (Is) 6-4 6-3
D Hantuchova (Slo) bt Barbara Schett (Aut) 7-5 6-1

First round:
I Majoli (Cro) bt R Grande (Ita) 3-6 6-4 6-4
E Dementieva (Rus) bt A Coetzer (SA) 6-3 6-0
M Casanova (Swi) bt L Raymond (US) 1-6 6-3 6-4
A Kremer (Lux) bt M Maleeva (Bul) 6-4 7-6 (7/5)