The Togliatty, Russia native announced her switch on social media.
The American converted his seventh match piont against Matteo Berrettini to win in Miami.
The Czech teen powered past Arthur Fils in Miami.
A stunning, running forehand pass from Grigor Dimitrov sparked his pulsating comeback win in Miami.
"She was pretty loosened up and just went for it," Iga Swiatek said after falling to 140th-ranked wild card Alexandra Eala in Miami.
Former British No. 1 Tim Henman joins Captain Yannick Noah on Team Europe.
"What impresses me most about Mirra Andreeva is her ability to stand up physically against the best players in the world," Andy Roddick said.
