Lee, 18, Is a Real Hit Against Rubin : Tennis: With no future in baseball, she scores upset at La Costa.

How exactly did 18-year-old Lindsay Lee get from a small town in Oklahoma all the way to the third round at La Costa?

Well . . . baseball was very, very good to her.

If that sounds confusing, then so was Lee’s introduction to tennis. A spectator was watching the 8-year-old Lee crush the ball and play shortstop in a boys’ all-star game at Owasso, Okla., and told her parents that the youngster should take up tennis, which she soon did.

“There’s no future in baseball for women,” Lee said earnestly.

So, the Colorado Silver Bullets are out of luck. And Lee’s future in tennis took a great leap forward Wednesday with her 2-6, 7-5, 6-3 second-round victory over eighth-seeded and 19th-ranked Chanda Rubin in the $430,000 Toshiba Classic.

In a third-round match, second-seeded Conchita Martinez needed six match points before defeating Ai Sugiyama, 4-6, 6-2, 6-3.

Lee, who needed to win two matches to qualify here, turned professional one day before her 17th birthday and appeared on the computer with a ranking of No. 547 last year. She played in satellite events at Acapulco, Vancouver and Sedona, Ariz., and qualified for her first WTA tour event in February.

But she made steady progress, qualifying for Wimbledon and beating Pam Shriver in the first round before pushing Natasha Zvereva to three sets in the second.

Lee’s parents had not been pleased with her move into the big time, at least initially.

“They did not like the decision of me turning pro, my ranking was 500,” said Lee, who will next play ninth-seeded Lisa Raymond. “They knew it was my dream, but they wanted me to go to college. After I started doing well, they liked the idea.”

Lee, now ranked 107th, displayed a powerful first serve and potent ground strokes against Rubin. Lee kept Rubin off balance with serves of 101 m.p.h. and spinning changeups of 63 m.p.h. The turning point in the third set came when Lee broke Rubin’s serve to take a 4-2 lead after trailing, 40-15.

Meanwhile, there was yet another player withdrawal because of an injury. Lindsay Davenport, seeded fifth, pulled out of doubles Tuesday and was unable to play her singles match Wednesday. Bothered by a stress reaction to her left shin, Davenport felt so much discomfort that she did not even try to test her leg in warm-ups.

“They’re not really sure what it is,” said Davenport, ranked No. 9. “I got some X-rays taken and it wasn’t a major stress fracture. I have to go in and get a bone scan of the area.”

She is questionable for next week’s tournament at Manhattan Beach.

Davenport first injured the leg before Wimbledon, but it held up on the more forgiving grass courts as she reached the fourth round. The hard courts at La Costa started taking their toll when she first practiced on Saturday.

Others who have withdrawn because of injury or illness include Steffi Graf, Magdalena Maleeva, Katerina Maleeva, Jana Novotna, Kimiko Date and Julie Halard.

In addition to Rubin, one other seeded player lost in the second round. Rachel McQuillan of Australia defeated No. 7 Nathalie Tauziat of France, 6-2, 6-4. Also, Asa Carlsson of Sweden defeated Tami Whitlinger Jones, 7-6 (7-2), 2-6, 7-6 (7-3).