Maria Sakkari powered her way into the semifinals of the WTA Finals in Guadalajara, Mexico after beating the world number two Aryna Sabalenka in a hard-fought game that lasted two hours 47 minutes.

Playing at the Estadio Akron de Tenis in the Mexican city, Sakkari won won the first set 7-6 but the Belarusian won the second set by the same margin. The first two sets were settled by tie breaks before Sakkari (rated number six in the world) dominated to win the final set 6-3.

Sabalenka was the top seed for the tournament after world number 1 Australia’s Ash Barty decided against defending the WTA Finals titles she won last year.

“It’s my first big win in Mexico, and I think I will never forget it,” a smiling Sakkari said after the match before a supportive crowd.

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She beat on Poland’s Iga Swiatek 6-2, 6-4 on Friday and Spain’s Paula Badosa 7-6, 6-4 on Sunday.

In the evening game against Sabalenka, the Greek served eight aces to Sabalenka’s seven and had just eight double faults on her serve compared to the Belarusian’s 19 and that proved to be a key difference.

“I think it was a roller coaster match from both of us. I was up a break, then she was up a break. It was just a matter of who took the chances. I think in the end I just played with heart and fought well, just turned things around,” Sakkari was reported as saying by ESPN.

Sakkari will next meet Anett Kontaveit for a place in the final. Kontaveit beat Garbrine Muguruza of Spain on Monday to set up the match against Sakkari.

In the other semi-final, Badosa is to meet Muguruza on Tuesday.