Serena Williams has admitted that her form in today's Red Group defeat to Simona Halep in the WTA Finals was "embarrassing".
The 33-year-old suffered her worst defeat since 1998 as Halep grabbed a 6-0 6-2 victory in Singapore.
"My forehand was off today," BBC Sport quotes Williams as saying. "I guess it went on an early vacation.
"Lord knows my serve was as well. My serve, I don't even know. My serve was at best in the 10 and under division in juniors. Yeah, it was actually embarrassing. I think embarrassing describes the way I played."
The defeat has brought an end to Williams's 16-match unbeaten run.
