Iga Swiatek could reach double figures for grand slam titles but Wimbledon may be a stumbling block, according to Marion Bartoli.
Speaking to Stats Perform, Bartoli said she did not expect any player on the WTA Tour to match the "greatness" of Serena or Venus Williams.
The Frenchwoman, who won the 2013 Wimbledon women's singles title, also claimed the level of competition is currently not as strong as it was for the previous generation.
She is sold on Swiatek, though, who added to her 2020 and 2022 French Open titles by winning the US Open earlier in September.
The 21-year-old Polish player has emerged as the clear world number one since Ash Barty retired in March, stringing together 37 consecutive wins at one point until Alize Cornet beat her in round three at Wimbledon.
A lull in her performances followed that exit on the grass, but Swiatek fought her way through the field to triumph in New York.
"I was very impressed by how Iga this time with the US Open came with absolutely zero confidence and still found a way to win, and that is really a champion's mind," Bartoli said.
""She played really not great tennis in Toronto, not good tennis in Cincinnati, didn't play that well before the US Open. Whatever she worked on with her coach, she went on and plugged in for seven matches and to win the title, which is very impressive.
"So I think the level it's not at the highest, but I think the way she has been able to handle the pressure and go for it and win was absolutely very, very impressive.
"And she will win more. For sure she will win more on clay, she will win more on normal, slower hardcourts. Maybe not grass, but slow hard court is really a good surface for her as well. So easily between five and 10 for Iga, easily."
With Serena Williams saying a fond farewell to competitive tennis at the US Open, the women's tour has lost a 23-slam giant. In Bartoli's mind, there may be nobody of the great American's prowess to emerge for many years to come.
She said: "I think it's unfair to ask any of the current women's players to be as dominating as Serena was, or you know Venus as well.
"You just can't ask them to be at that level of greatness. You get that one out of a century or even two centuries. So I think we will have to wait a while before we get the next Serena Williams.
"And even Coco [Gauff] has talked about it, [saying] 'I'm not Serena, I will probably not get 23 grand slams like Serena you know, so stop putting pressure on me'.
"I think they're just trying their hardest, they're just trying their best, but obviously as Maria Sharapova said and I agree with her, the level of competition we used to have when all of us were playing was I think higher than what it is now."
Bartoli pointed to the example of Emma Raducanu, as a near-unknown, winning the US Open last year. She said that triumph for the British teenager was "out of any rational thoughts".
"This year she lost first round [to Cornet] and she dropped to 80 in the world," Bartoli added.
"You know that someone at 80 and someone at five, there is not so much of a difference in terms of level. And that's why you see those sort of upsets and constant change."