Newly-crowned Australian Open champion Madison Keys would have expected to receive invitations to more tournaments in the coming months but the ATX Open in Austin was forced to drop the American after she climbed into the top 10 in the rankings.
Keys beat the top two seeds, Iga Swiatek and defending champion Aryna Sabalenka, in Melbourne to win her first Grand Slam title, catapulting the 29-year-old into the top 10 and a career-high seventh in the rankings.
But since the February 22-March 2 ATX Open is a WTA 250 event, only one top 10 player is allowed in the draw unless the defending champion also returns as a top-10 player.
Keys had agreed to play when her ranking was 21st but so did American world No 6 Jessica Pegula, who will be participating in the tournament for the first time.
"We love Madison and have been anticipating for months the excitement of her playing here in Austin for the first time," tournament director Christo van Rensburg said in a statement.
"While we wish the Top 10 rule didn't apply to our tournament, we respect the rules of the WTA.
"That said, Madison's Grand Slam title and subsequent Top 10 world ranking are both something to celebrate. We can't wait to invite Madison again to future ATX Opens."
Keys has reached only one other Grand Slam final – at the US Open in 2017.
Her Australian Open triumph came in her 46th Grand Slam, the third-most for a maiden major trophy in the professional era.