Madison Keys is out of the ATX Open in Austin because a WTA rule is preventing her from competing in the tournament. When the entry list for the WTA 250 tournament in Austin was released, the American tennis star's name was on it.

Keys, who rose to world No. 7 after winning her first Grand Slam title, had entered the WTA 250-level ATX Open in Austin, Tex., which begins February 24. The American entered the tournament as world No. 21, with fellow American Jessica Pegula entering as world No. 6.

Madison Keys has been forced to pull out of next month’s ATX Open in Texas as a direct result of her winning the Australian Open. Keys sent a shiver down the spine of the tennis world when she toppled back-to-back Australian Open champion Aryna Sabalenka in last week’s Melbourne showpiece.

Due to an odd rule preventing more than top 10 player participating in a WTA 250 tournament, the ATX Open announced Tuesday that Keys will no longer be eligible to participate in the event. The Austin-based tournament already has No. 6 Jessica Pegula committed to play.

Madison Keys is currently one of the biggest names in women’s tennis, but her successful title run at the Australian Open has come at a cost. The American lifted her maiden Grand Slam trophy after defeating two-time defending champion Aryna Sabalenka in the final at Melbourne Park.