SINGAPORE - It was far from being her most compelling victory, but Garbine Muguruza got the win she wanted on Friday afternoon, labouring to a 6-4, 4-6, 7-5 win over Czech Republic's Petra Kvitova.

The result means the Spaniard, the new world No. 3, tops White Group with three victories to earn a spot in the semi-finals on Saturday.

Kvitova, a two-time Wimbledon champion, remains in the mix despite suffering two defeats in the group. She finished second in White Group and earns a spot in the final four after good friend and team-mate Lucie Safarova beat Angelique Kerber 6-4, 6-3 in the day's other singles tie.

Said Muguruza, who has also qualified for the doubles semi-finals with Carla Suarez-Navarro: "Petra is an amazing player. Today she played great. I was so nervous, she makes me play really concentrate, and I've to give my best.

"But I'm super happy of this ending. Hopefully I can continue winning and play like this."

Safarova was eliminated from the tournament before even starting the match.

In the Red Group, Maria Sharapova and Agnieszka Radwanska have progressed to the semi-finals on Thursday.

Muguruza will play Radwanska, while Kvitova will meet Sharapova in the semi-finals.