CARLSBAD, Calif. -- Defending champion and formerly top-ranked Yani Tseng was dropped from the Kia Classic field after missing her 9:10 a.m. pro-am tee time Wednesday.

"I'm embarrassed to admit that I wasn't feeling well last night and accidentally overslept and missed my tee time for the pro-am this morning," Tseng said in a statement released by the tour. "I was extremely excited to compete this week to defend my title at the Kia Classic and to try to regain the No. 1 spot. This was an unfortunate mistake and I want to apologize to Kia, my sponsors and all of the fans."

On Sunday, Stacy Lewis won the LPGA Founders Cup in Phoenix to end Tseng's 109-week run at No. 1.

Tseng is winless in 23 events since her Kia Classic victory last year. The 15-time LPGA Tour winner tied for 59th last week in Phoenix. She opened the season with a second-place finish in the Women's Australian Open, tied for third in the LPGA Thailand and completed the Asian swing with a tie for 28th in Singapore in the HSBC Women's Champions.

The 24-year-old Taiwanese star will return to play April 4-7 in the Kraft Nabisco Championship, the first major championship of the year, at Mission Hills in Rancho Mirage.

Lewis has won the last two events.