Tseng missed her pro-am tee time Wednesday at Aviara Golf Club in Carlsbad, Calif., and per LPGA regulations she was withdrawn from the tournament.
The following is a statement from Tseng:
"I'm embarrassed to admit that I wasn't feeling well (Tuesday) night and accidentally overslept and missed my tee time for the pro-am (Wednesday) morning. 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. The Kia Classic is one of my favorite tournaments and I have so many great memories in San Diego. I can't wait to come back here next year."
Tseng, who has been mired in a slump, lost her No. 1 ranking this week to Stacy Lewis. Tseng had been at the top for 109 weeks.