Ana Ivanovic "very disappointed" by defeat to Serena Williams

Ana Ivanovic has admitted that she is "very disappointed" by her defeat to Serena Williams at the WTA Finals in Singapore.

The Serbian lost her opening match of the tournament on Monday as she went down 4-6 4-6 to the defending champion.

"I'm definitely very disappointed I made a few easy errors in the last service games of both sets," Ivanovic is quoted as saying by the WTA's official website. "I had a break point at 4-4 [in the first set], which I didn't take and kind of got down a little bit on myself.

"Then I rushed a little bit in the next service game, so that was a little bit disappointing. I felt I created lots of chances, especially off the ground."

Ivanovic and Williams have been drawn in the Red Group alongside Simona Halep and Eugenie Bouchard, while Maria Sharapova and Petra Kvitova are among the players in the White Group.