Mouratoglou admits to coaching Serena during US Open final

Patrick Mouratoglou admitted to coaching Serena Williams during the US Open final, but believes the American great never received his message.

The 23-time grand slam champion suffered a 6-2 6-4 loss to Naomi Osaka in a contentious decider in New York on Saturday.

However, the final was overshadowed by Williams receiving three code violations – coaching, racket abuse and verbal abuse – and eventually a game penalty on Arthur Ashe Stadium.

Mouratoglou said he had attempted to help Williams, but added coaching was common in almost every match.

"I'm honest, I was coaching. I don't think she looked at me so that's why she didn't even think I was," he told ESPN.

"But I was, like 100 per cent of the coaches in 100 per cent of the matches so we have to stop this hypocritical thing. Sascha [Bajin, Osaka's coach] was coaching every point, too.

"It's strange that this chair umpire [Carlos Ramos] was the chair umpire of most of the finals of Rafa [Nadal] and [his uncle] Toni's coaching every single point and he never gave a warning so I don't really get it."

Williams was surprised to hear of Mouratoglou's admission, saying she had sent her coach a text asking for an explanation.

"We have never discussed signals. I don't even call for on-court coaching. I'm trying to figure out why he would say that," she said. "I don't understand. I mean, maybe he said, 'You can do it.'

"I was on the far other end, so I'm not sure. I want to clarify myself what he's talking about."

Asked if the umpire had to give her the warning, Williams responded: "No, because I wasn't being coached.

"If I look at my box and they say, 'C'mon' or 'Good job', I don't know what else to do. After that I didn't even look at my box anymore."