SOFIA, Bulgaria (AP) Garbine Muguruza's perfect serve helped her to a surprise 6-2, 6-1 victory over top-seeded Ekaterina Makarova of Russia in the group stage at the season-ending WTA Tournament of Champions on Wednesday.
The WTA's rising star from Spain, who replaced the injured Samantha Stosur, needed just 69 minutes to cruise past the Russian favorite.
''She played very aggressive and didn't give me any chances,'' an exhausted Makarova said after the match.
''I played very good today, indeed,'' Muguruza said, adding: ''I'm here to win the tournament.''
In the Sredets group, Andrea Petkovic of Germany outlasted Bulgaria's Tsvetana Pironkova 7-5, 6-2 for her first victory at the tournament.
Dominika Cibulkova of Slovakia defeated Spain's Carla Suarez Navarro 7-5, 6-4 in the group's second match.
Cibulkova, the 2014 Australian Open finalist, started aggressively and took a 5-0 lead in the first set. Suarez Navarro rallied to 5-5, but Cibulkova managed to close the set out before going on to secure her second straight victory at the event.