Former Serena Williams coach admits having had a few disputes with the American star over her weight

Serena Williams made an indelible impact on tennis. With 23 Grand Slam singles titles, she ranks as the second-most decorated female player in history, behind only Margaret Court, and became a global icon over her more than two-decade career. The final stage of her career was guided by Patrick Mouratoglou, one of the sport’s most respected and demanding coaches.

In a recent interview with The Guardian, Mouratoglou made a controversial statement about playing professional tennis carrying extra weight. “Tennis is a sport where you cannot afford to have excess weight,” the former Williams coach said.

“First, because of the strain on your joints—if you struggle here, your chances decrease significantly. Second, tennis requires constant changes of direction at high speed; even a single extra kilo can make a big difference,” he added.

Mouratoglou reflects on Williams’ career and challenges with weight

During his time coaching Serena Williams, Mouratoglou helped her win 10 Grand Slam singles titles, an Olympic gold medal, three consecutive year-end championships, and regain the No. 1 spot in the WTA rankings. However, the French coach also recalled one of the challenges he faced with the American legend.

Serena Williams with Patrick Mouratoglou during a practice session. (Michael Dodge/Getty Images)

“In Serena’s case, she was older, and we knew her body wouldn’t respond like it used to, so the risk of injury was even higher,” Mouratoglou explained. He also revealed that they occasionally clashed over Williams’ weight: “In the past, we had a few disputes about her weight. I remember she didn’t like me bringing it up and said I was judging her”.

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“I kept telling her that I didn’t care about her appearance—that wasn’t my job. My job was her tennis. But if she wanted to get back to the top and make history, we had to be efficient at every level, including physically. Now I see that she’s leaner, and if she had been in this condition years ago… the results would have surely been better,” Mouratoglou added.

Over her storied career, Williams amassed 23 Grand Slam singles titles, 14 doubles titles, four Olympic gold medals, and 73 overall singles trophies, cementing her status as one of the greatest players in tennis history.

Mouratoglou reflects on his split with Naomi Osaka

Patrick Mouratoglou coached Naomi Osaka until July 2025, and the French coach recently explained why their professional relationship ended. “The results weren’t strong enough, which made sense,” Mouratoglou said. “We did a lot of good work, especially in practice, but anything can go wrong when it comes to competing. I saw her improve a lot—her mentality was excellent—but she didn’t perform as well during matches, and that ultimately held her back”.

Looking back, Mouratoglou admitted he could have done more: “I didn’t do a good enough job; otherwise, the results would have been there. I also think that being my student was a bit heavy for her, given the many years I spent with Serena, which she mentioned several times. I never figured out how to take that pressure off her, to help her feel freer. Surely, without that pressure, she could have expressed herself more openly, but there are no hard feelings—she remains a great competitor”.