The Tsitsidream came true on Sunday in Antwerp.
Ben Shelton, Sunday's Tokyo champion, rounds out the quartet at No.15.
The Dane hopes to work his way out of a tailspin and into the Turin field.
Meanwhile, Daniil Medvedev will bid for a title defense in Austria.
The eight-team field is set for the WTA Finals, which commence on October 30 in Cancun, Mexico
"If I set dates and I don't meet them, I'm adding disappointments that I don't need," said Rafael Nadal of his comeback aim.
World's top two to join Aryna Sabalenka and Ons Jabeur playing Riyadh Season Tennis Cup in Saudi Arabia.
