Former world number one Garbine Muguruza booked her spot in the semi-finals of the WTA Finals with a 6-4 6-4 win over in-form eighth seed Anett Kontaveit.

Kontaveit was already assured of a semi-final berth prior to Sunday's matchup but the Group Teotihuacan victor was riding a 12-match winning streak.

However, that unbeaten run came to an end at the hands of two-time grand slam champion Muguruza in straight sets.

Muguruza, who lost her Finals opener before outlasting Barbora Krejcikova in the second match, needed to win to advance and the Spanish star delivered at the year-ending championship in Guadalajara.

For the first time this tournament, Kontaveit dropped serve – Muguruza breaking in the opening game to set the tone in Mexico.

Muguruza rolled through her service games until trying to close out the set at 5-4, Kontaveit earning opportunities, but she was unable to convert as the sixth seed clinched.

The second set followed a similar theme after Muguruza broke Kontaveit's serve in the first game, and she maintained that advantage until facing a break in her bid to progress to the semis.

Muguruza navigated the break point as she earned a showdown with fellow Spaniard Paula Badosa – the winner to become the first Spanish woman to reach the final since Arantxa Sanchez-Vicario was runner-up in 1993.

Since the round-robin format was re-introduced in 2003, this will be only the second time the sixth, seventh and eighth seeds (Muguruza, Badosa and Kontaveit) all advanced to the WTA Finals semis after 2018.

WINNERS/UNFORCED ERRORS 

Muguruza – 13/20
Kontaveit – 17/29

ACES/DOUBLE FAULTS 

Muguruza – 7/3
Kontaveit – 2/3

BREAK POINTS WON 

Muguruza – 2/6
Kontaveit – 0/3