SINGAPORE (AP) Second-seeded Garbine Muguruza improved to 2-0 in group-stage matches at the WTA Finals by beating Angelique Kerber 6-4, 6-4 Wednesday.

In the day's other match, fourth-seeded Petra Kvitova defeated fellow Czech Lucie Safarova 7-5, 7-5 for her first win in Singapore.

Muguruza broke Kerber twice in each set to wrap up the win in 1 hour, 38 minutes. The Spaniard is making her debut at the season-ending tournament and beat former champion Kvitova in their first round-robin match.

''You never know how it's going to go here when you come the first time,'' Muguruza said. ''For sure I'm very happy with how it is going.''

Kvitova improved to 8-0 in career matches against the ninth-seeded Safarova, who fell to 0-2 in her first appearance at the season-ending tournament. Kvitova and Kerber are 1-1, with all four still in contention for a spot in the semifinals.