Also, Iga Swiatek and Barbora Krejcikova clash in Seoul, and Italy and Ukraine battle for a spot in the Billie Jean King Cup final.

The American then watched Jessica Pegula and Taylor Townsend defeat Kazakhstan's Elena Rybakina and Yulia Putintseva in a winner-take-all doubles match.

The U.S. beat Slovakia in Bratislava on the strength of late call-ups Hailey Baptiste and Bernarda Pera.

The U.S. next faces host nation Slovakia on Sunday with the winner going through to the finals.

That Porsche she won last year in Stuttgart is finally getting a workout.