Wednesday September 30th, 2015

Serena Williams may not be ready for a return to competition after her surprise U.S. Open semifinals loss to Roberta Vinci earlier this month, her coach Patrick Mouratoglou told ESPN's Melissa Isaacson.

The upset ended Williams's hopes of completing the calendar-year Grand Slam. A U.S. Open title would have marked Williams's fifth straight Grand Slam title.  

Williams is scheduled to compete at the China Open next week and at the WTA Finals in Singapore at the end of October, but Mouratoglou said that Williams's motivation could be an issue. 

“When she lost in Toronto [in August], she was very disappointed, but we went back to practice the morning after because she wanted to win the US Open,” Mouratoglou told ESPNW. “But after this year and the three Grand Slams [she won in 2015], the question is how high her motivation is to play those tournaments. I don't think she should play if the motivation is not really high.”

• Daily Bagel: Venus Williams wins 700th career match in Wuhan 

Williams, 34, needs one more Grand Slam title to tie Steffi Graf's record of 22, the highest total in the professional era. 

“I don't doubt she will have the motivation to win more Grand Slams and reach records,” Mouratoglou said. “I'm just thinking about the end of the season, and I don't know how high the motivation is, and I don't think she should go play competitions if her motivation is not high enough.”

- Xandria James

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