Muguruza lost her only previous match against Johanna Konta
2018 WTA Finals Venue: Singapore Sports Hub Dates: 10-19 November Coverage: Live coverage of the semi-finals and final on BBC Two and online.
World number two Garbiñe Muguruza became the first Spanish woman to win the season-ending WTA Finals in Singapore.
The Wimbledon champion defeated Johanna Konta 6-4 6-1.
World number one Simona Halep and Agnieszka Radwanska both failed to qualify for the eight-woman tournament, which is played for the first time since 2013.
British number one Konta is among eight players to reach the semi-finals.
She will face France’s Caroline Garcia in one semi-final, with Muguruza up against Petra Kvitova, the two Czechs meeting on Wednesday and Garbine Muguruza facing Venus Williams.
“It’s a privilege to have played Johanna in two finals, so yeah, I’m very happy to get this one,” said Muguruza.
Last season’s final between Muguruza and Angelique Kerber was suspended because of a power failure at the Singapore Sports Hub – although the venue has since undergone a £115m refurbishment.
With the roof closed again on Tuesday, the routine 12-minute match was made a lot more difficult by Muguruza, who won 13 of the final 16 points on serve and connected on 41% of her first serves.
Konta, who leads the head-to-head series with Muguruza 5-4, showed a marked improvement on her last-eight defeat by Angelique Kerber but was in danger of losing at 0-4 at one stage and was broken once in each set.
The 28-year-old made it two defeats from three matches and has won only one of five matches against Garcia this year, while Muguruza has lost four of her seven matches against the Bulgarian, including the 2016 French Open final.