Nobody would blame Serena Williams for taking her racket and going home for the 2015 season. But her coach feeling compelled to explain where her head is at is curious.

Patrick Mouratoglou said the disappointment Williams has experienced in falling short of winning the calendar Grand Slam has him doubting whether she should play any more tennis this year, espnW is reporting.

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Williams is scheduled to participate in the China Open next week and the season-ending WTA Finals in Singapore at the end of October, according to The Guardian.

"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 said in a phone interview with espnW from France. "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."

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Williams warned media she did not wish to discuss her disappointment after bowing out in the semifinals of the U.S. Open with her three-set loss to veteran Roberta Vinci and denied that the pressure of trying to win the calendar slam had an effect on her play.

Mouratoglou refuted Williams' post-match statement.

"Because she lost [the semifinal] match, she says to me her season is not good," he said. "But I like that because it's just about having high expectations and that's what champions have and I think the same way."

Mouratoglou blamed himself for not having Williams mentally prepared for her semifinals match against Vinci. He suggested Williams may have been taking Vinci lightly and was already looking ahead to the final -- which would be unusual for someone with Williams' big-match experience.

He said Serena simply needs more time to get her mojo back.

"I don't doubt she will have the motivation to win more Grand Slams and reach records," he said. "She was two matches away from something really big, so it was very painful," Mouratoglou said. "Any loss is very painful for her, but this one even more than usual, so it just takes time to recover from it."

Williams, who turned 34 over the weekend, is one Grand Slam title behind Steffi Graf (22) for second all-time. Margaret Court holds the all-time record at 24.

Williams has until January to rekindle her fighting spirit when the Australian Open comes back around. But the hint of fragility on Williams' part begs the question: What happens if she loses that first Grand Slam? Will her inner demons continue to grow to the point of affecting her dominance?

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