Naomi Cavaday earned a place in the second round of the DFS Classic when she stunned Vasilisa Bardina.
The hard-hitting Cavaday enjoys the Edgbaston surface
Despite being ranked 182 places below the Russian, the British number four dominated, cruising to a 6-2 6-1 win.
Cavaday then watched former British number one Elena Baltacha go out after a lengthy three-set battle with Venezuelan Milagros Sequera.
Anne Keothavong, the current British number one, also lost in three sets to Austrian teenager Tamira Paszek.
The British number one, who has won just one of seven matches in Birmingham, won the first set but never fully recovered from trailing 3-0 at the start of the second.
She fought back to level at 4-4 in the deciding set but dropped her serve and her 16-year-old opponent served out for a 2-6 6-2 6-4 win.
Baltacha, who has sunk to 437th in the rankings after missing nine months of last season following back surgery, went down 6-4 1-6 7-5.
It was a fighting effort against the world number 54, in a compelling encounter that lasted two hours and 18 minutes on centre court.
This is my biggest win by a long way, my other biggest win was last year here again so I am really comfortable at the DFS
The 18-year-old Cavaday, who was given a wild card for the Edgbaston event, was ecstatic after her victory over the world number 61.
"This is my biggest win by a long way, my other biggest win was last year here again so I am really comfortable at the DFS," the Kent-born player said.
"I really enjoy it here. I know she has been struggling recently since she finished with her coach. She gave it her best shot and I think I played a good match."
The youngster, who has been confirmed as a wildcard entrant at Wimbledon, said the win vindicated her new more relaxed approach to games.
"I have been really enjoying my tennis this year and I think it has been helping me finish off matches because I'm not getting too wrapped up in anything that can be too distracting," she said.
Cavaday's reward for beating Bardina is a meeting with fifth seed Marion Bartoli of France.
Russia's Elena Likhovtseva became the first player through to the last 16 when she defeated 12th seed Agnieszka Radwanska of Poland, in a second-round match.
Third seed Daniel Hantuchova, of Slovakia, gained a 6-2 6-4 victory over Olga Govortsova, of Belarus, while fourth seed Na Li, of China, overcame Russian Yaroslava Shvedova 4-6 6-2 6-0.
Two seeded players lost in the first round on Tuesday, as number 11 Olga Poutschkova was upset 6-0 6-0 by Angelique Kerber of Germany and number 10 Severine Bremond was defeated 4-6 6-3 6-4 by Alicia Molik.
Former Wimbledon champion Maria Sharapova begins her campaign on Wednesday against American qualifier Lilia Osterloh, while second seed Jelena Jankovic is first up against Bulgaria's Tsvetana Pironkova.