Serena Williams’s coach says the world No.1 may skip the remainder of the season as she struggled to come to terms with her US Open disappointment.

The American was knocked out in the tournament’s semi-finals, falling just two victories short of sealing the first calendar grand slam since 1988.

And now Patrick Mouratoglou has told ESPN that Williams needs a break to deal with the mental anguish.

“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, and when the motivation comes back, which I don’t doubt it will, then it will be time to start tournaments again.”

Williams, who has already clinched the year-end world No.1 ranking, is scheduled to return in next week’s China Open and the WTA Finals at Singapore next month.

“After this year and the three Grand Slams, 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,” Mouratoglou said in a posting on ESPN’s website.

Mouratoglou does not see Serena running out of time just a few days after her 34th birthday.

“It’s not time to doubt whether age will affect her,” he said. “She has a lot of time left.”