Two-time grand slam champion Coco Gauff has split with her coach just days out from the US Open main draw.

The 2023 US Open and 2025 Roland Garros champion has parted ways with Matt Daly after just under 12 months together, but is continuing to work with JC Faurel, who will be joined by incoming biomechanics expert Gavin MacMillan.

Daly replaced Brad Gilbert last year, who was brought in after Gauff’s fourth-round US Open exit.

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MacMillan, who is the founder of Sport Science Lab, has formerly worked with current world No.1 Aryna Sabalenka when she had issues with her serving action.

He was seen working with Gauff at Arthur Ashe Stadium on Wednesday.

Darren Cahill, the Australian coach of men’s world No.1 Jannik Sinner, said MacMillan shapes as a wildcard for Gauff.

“A lot of things add up and this could be a really good relationship,” Cahill said on ESPN.

“He’s very thorough. I’ve spoken to him many, many times before and the fact that he’s got experience with different athletes from different sports, both male and female, he uses the new technology, he goes to the video a lot, really breaks down the biomechanics.”

Chris Eubanks, who lost a men’s qualifier for the US Open on Tuesday (local time), also appeared on court while Gauff practiced.

“He’s always got her best interests at heart, so he’s a great friend of Coco’s,” Cahill said.

Patrick McEnroe added: “She wants to get better and she’s open to hearing from different people.

“But it does tell you that there continues to be a problem with her serve, as it’s been consistently inconsistent.”

The American world No.3 was at the top of her game when she won the French Open earlier this year, but is 4-4 since then.

“It’s crazy how quickly you can lose your confidence,” Mary Joe Fernandez told ESPN.

“You win a grand slam title and you think you’re riding this wave and it’s going to carry over and it doesn’t always happen.

“For Coco, she had a really tough draw at Wimbledon, playing (Dayana) Yastremska in the first round, a big powerful hitter, so that was I think unfortunate for her not being able to work her way into the tournament.

“And then on the hardcourts she has struggled, primarily with her serve. I think that’s the one shot that if she can settle down and find a way to feel confident that she’s going to make a majority of her first serves and rely on what she did a couple years ago, winning when she wasn’t playing her best and making her opponents beat her somehow, making it more physical, then I think she’ll get back to it.”