Alicia Molik has declared Naomi Osaka and the rest of the US Open field "isn't close" to Ash Barty's level ahead of the final grand slam of the year.
Osaka is the defending champion at Flushing Meadows and has been installed as the favourite by some bookmakers.
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However she's only played a handful of matches since withdrawing from the French Open after the first round and subsequently skipping Wimbledon.
Meanwhile Barty comes into the US Open having won her second grand slam title at Wimbledon and claiming the Cincinnati Masters trophy for her fifth title of the year.
“I’m not quite sure Osaka has been able to prove she can play at a high level, consistently, throughout every tournament since she came back in the last couple of months,” Molik told the Sydney Morning Herald.
“When Osaka has her best success, she blows people off the court with some really convincing wins. We’re seeing less and less of those.
“Her confidence has dipped a bit and I think you see that throughout her matches. She looks a little more vulnerable against a wider array of plays."
Australia's Billie Jean King Cup captain said no other player on the tour is close to Barty's current level of form.
Osaka will be back in the spotlight when the US Open begins on Monday, with crowds back after the coronavirus pandemic forced them away in 2020.
"It will definitely feel a bit different," Osaka said.
"I don't really know how to describe it, but I kind of had to get over the feeling of people's gazes feeling a bit different to me.
"At the same time I started to tell myself that it is what it is. I can't really change people's perception of me.
"It might make me feel a little bit nervous. But first rounds always make me feel a little nervous."
Ash Barty's challenging US Open draw
Barty will have to be wary from the get-go after drawing former finalist Vera Zvonareva as her first-round opponent.
Australia's World No.1 has never played the 36-year-old Russian, who reached the final both in New York and Wimbledon in 2010.
The Muscovite mother has these days slipped to 101 in the world rankings, but as a former World No.2 who's beaten Petra Kvitova this year, still clearly demands the utmost respect from the Wimbledon champ.
The draw could see Barty face a second-round clash against rising French star Clara Burel.
The last-32 would then potentially have her pitted against Russian Veronika Kudermetova, the No.29 seed who Barty's already beaten comfortably this year on the Roman clay.
In the last-16, her friend and Australian Open runner-up Jen Brady is projected to await as Barty seeks to make the quarter-finals in New York for the first time.
Then the last-eight may throw up a real blockbuster with last year's French Open champion Iga Swiatek, while Barty might have to fight past 2019 US Open winner Bianca Andreescu in the semis.
She's seeded to meet No.2 seed Aryna Sabalenka in the final but the Belarusian might have to get past No.3 seed and reigning champ Osaka in the semi-final.
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