Australian Open champion Madison Keys is no longer able to play at a WTA tournament in the U.S. in February, after her success in Melbourne made her too highly ranked to enter. 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. But under WTA rules, 250-level tournaments (the lowest