It has not been a good week for Yani Tseng.

Fresh off losing her number one world ranking to Stacy Lewis, Tseng was forced to withdraw from this week's Kia Classic after she missed her pro-am tee time on Wednesday morning.

What's worse is that Tseng is the defending champion of the event.

"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 LPGA 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 ended Tseng's 109-week run at No. 1 when she won the LPGA Founders Cup in Phoenix.

Files from the Associated Press were used in this report