Serena Williams US Open 2013: Boyfriend Boosts Tennis Career? Coach Patrick Mouratoglou Touts 100-Victory Win With Rumored Girlfriend

Serena Williams' coach and rumored boyfriend Patrick Mouratoglou touted her performance in the US Open 2013, saying "#serena broke 100 victories with tonight's win since we work together."

But some say the X-factor in Serena Williams' quest for a fifth U.S. Open could be the presence of her parents, leaving fans wondering how her relationship with coach and rumored boyfriend Patrick Mouratoglou will affect her chances.

Richard Williams, Serena Williams' father, boycotted attending the Wimbledon 2013 tournament, where Serena Williams had an early dismissal, because he isn't happy she's dating Patrick Mouratoglou - the most likely cause of his discontent lies in the French coach's marital status, AOL Entertainment reports.

Patrick Mouratoglou is in a divorce case with ex-wife Clarisse Mouratoglou and is still dating Serena Williams.

While Serena Williams' mother has not reported any disapproval with her relationship, her father is certainly not in favor of it.

Patrick Mouratoglou also showed his support for Serena Williams' sister, Venus, on Twitter last week as she advanced at the Western & Southern Open in Ohio, leaving fans wondering if he's trying to tighten his relationship with his rumored girlfriend's family.

"#Venus playing much better now. More consistent and aggressive. In control of the rallies," the French tennis coach posted on Monday.