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The Dutch coach has worked with several top WTA players including Conchita Martinez, Arantxa Sanchez Vicario, Maria Sharapova, Ana Ivanovic and Andrea Petkovic.
He has picked out the players who he thinks can further build on their successes.
“Garbine Muguruza, Ash Barty and Bianca Andreescu have a chance to win five Slams, but [Sofia] Kenin and Andreescu, or Osaka, they came up very young, and it's always easier to come up than to stay as a top player," he told TENNIS.com.
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“They all have some opponents they do not like, such as Muguruza - she is 0-4 record against [Andrea] Petkovic, but she has a chance because with Conchita [Martinez], she has a coach who really understands the game."
The 76-year-old added: "I like Ash Barty the most at the moment.
"I thought a few years ago that [Sloane] Stephens would be a candidate to follow Serena, but that was very disappointing.
It was impressive Andreescu won the  US Open, but what kind of injury she had that took her so long to come back.