"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. "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 incident occurred two days after the 24-year-old Taiwanese player lost her No. 1 ranking to Stacy Lewis.
Tseng had been the top-ranked women's golfer for 109 weeks. She defeated Sun Young Yoo by six strokes in last year's Kia Classic.