Garbine Muguruza has advanced to the semifinals at the WTA Finals in her first appearance.

The 22-year-old Spanish-Venezuelan tennis player beat former champion Petra Kvitova 6-4, 4-6, 7-5 on Friday to reach the semifinals.

Muguruza finished the round-robin stage 3-0 and needed to win only one set against Kvitova to earn a semifinal berth.

The other three players in the group all finished 1-2, but Kvitova advanced because of more sets won.

After losing to Muguruza, Kvitova needed the already-eliminated Lucie Safarova to beat Angelique Kerber without dropping a set, and her compatriot came through by winning 6-4, 6-3.

Kvitova will play Maria Sharapova, who won the other group, with Muguruza facing Agnieszka Radwanska in the other semifinal.

In a match that featured 15 breaks of serve, Muguruza converted her fourth match point with a backhand crosscourt volley to win in 2 hours, 33 minutes.

The Spaniard is also into the doubles semifinals with countrywoman Carla Suarez Navarro, and said the heavy workload is taking a toll.

“For sure I’m tired today,” Muguruza said. “It’s going to a challenge for me to see how much my body can handle, because now I don’t have a day off. It’s great to be in my position I think now, to be playing singles and doubles semifinals.”