CANCUN - Second-ranked Iga Swiatek defeated world number one Aryna Sabalenka 6-3, 6-2 on Sunday to reach the title match of the WTA Finals, where she will face fellow unbeaten Jessica Pegula.
By downing the reigning Australian Open champion, Swiatek denied Sabalenka a victory that would have clinched the year-end top ranking for the 25-year-old from Belarus.
Instead, reigning French Open champion Swiatek of Poland can claim the year-end world number one spot for the second consecutive season by defeating American Pegula in Monday's championship match.
"I feel like it's still a long way away because I feel like tomorrow's match will be the toughest one," Swiatek said. "We can talk about it tomorrow after the match. I'm just going to continue doing what I've been doing."
Sabalenka overtook Swiatek for the top ranking two months ago but would keep it only if Pegula wins.
Pegula beat compatriot Coco Gauff 6-2, 6-1 in an hour on Saturday to reach the WTA Finals championship match, stretching her overall win streak to nine matches.
Swiatek owns a 5-3 career edge over Pegula in their rivalry but the American has won two of their three meetings this year, at the United Cup and in an August semi-final on Montreal hardcourts. Swiatek beat Pegula in this year's Doha final.
"I can't truly tell you the keys for tomorrow," Swiatek said. "I'm going to work on that."
The final was delayed to Monday due to rain that played havoc with the week's schedule at the outdoor hardcourts in Cancun, Mexico -- including stopping Swiatek and Sabalenka only three games into their semi-final on Saturday night.