Ash Barty's coach Craig Tyzzer has sensationally declared she will never win the US Open unless they change the balls used at the New York grand slam.
Barty won her maiden Australian Open title on Saturday night, joining Serena Williams, Roger Federer, Rafa Nadal and Novak Djokovic as the only active players with grand slam titles on all three surfaces - hard, grass and clay.
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She also joined Serena as the only player to win their first three majors on three different surfaces following her 2019 French Open and 2021 Wimbledon triumphs.
The only major Barty is yet to win is the US Open, but according to coach Tyzzer, he can't see it happening anytime soon.
Barty suffered a shock third-round loss to World No.43 Shelby Rogers at Flushing Meadows last September in what has turned out to be the Queenslander's only defeat in her past 19 hardcourt outings.
The World No.1 won prestigious events on the surface in Miami and Cincinnati last year in the lead-up to the US Open, but Tyzzer says her early exit from Flushing Meadows was no coincidence.
"The US Open really needs to change the ball for the girls. The fact they still use a different ball for guys and girls, it's a terrible ball for someone like Ash," Tyzzer said on Saturday night.
"Even in Cincinnati, when they use the US Open ball outside, she could actually get some loft out of the court.
"But the ball itself is so light. It was the only tournament last year and really for two years where she uses gut racquet (strings) but I had to change her to a poly just to get any sort of control of the ball.
"If they keep that ball the same, no one like Ash will win that tournament."
Tyzzer said the fact that Emma Raducanu and Leylah Fernandez made it to the final was a sign that something was amiss.
With no disrespect to the two shock finalists, Tyzzer said he wasn't the least bit surprised to see an all-unseeded final in New York last September.
"You see the result at the US Open, it was two players who, you go, 'Wow, that was, two different players won that?' There's no surprise when the ball is like it is," he said.
"And I don't know the reason why it's the only tournament that has separate ball for the guys and girls.
"So if they don't change the balls, she (Barty) won't win the US Open."
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Barty said she was humbled to have joined such an elite list of players with majors on all three surfaces.
"I feel very humble to be in such a select group," Barty said in the aftermath to her 6-3 7-6 (7-2) win on Rod Laver Arena.
"To be honest, I don't really feel like I belong with those champions of our sport.
"There's still work to be done, without a doubt. I'm still very much learning and trying to refine my craft and trying to learn every single day to get better and better.
Active players with a Grand Slam on hard, clay, and grass:
— US Open Tennis (@usopen) January 29, 2022
"It's amazing to be able to have this experience and this opportunity on three different surfaces and be really consistent across the board.
"Ultimately, that was one of the biggest challenges that Jim set out for me when I was young, to be a complete player and be really consistent across all surfaces and be able to play on all surfaces.
"So to have a grand slam title on each surface is pretty amazing. I never probably thought it would ever happen to me.
"So very, very lucky and very humbled and privileged to be able to be a part of it."
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