Iga Swiatek is one win away from reclaiming the world No 1 ranking after easing past Aryna Sabalenka 6-3, 6-2 in the delayed semi-finals of the season-ending WTA Finals in Cancun on Sunday.
The win by the impressive Swiatek sets up a final showdown with American Jessica Pegula, and the second-ranked Pole can end the year on top if she is able to lift the trophy.
Sabalenka, the current world No 1, ended Swiatek's WTA Finals campaign in the penultimate stage a year ago but lacked her usual lethal power in Mexico, as a flurry of forehand errors undermined her best efforts.
The match began on Saturday, but officials were forced to suspend it with the Pole up 2-1 in the first set due to inclement weather.
Four-time major winner Swiatek wrested the momentum immediately when play resumed on Sunday, and broke Sabalenka's serve in the fourth game.
Sabalenka was unable to set up a single break point in the second set, and she whacked her racquet in frustration after she sent a shot beyond the baseline to hand her opponent the break in the third game.
Swiatek kept her composure, committing few errors as she converted another break point with a mighty overhead smash in the seventh game.
The 22-year-old pumped her fists and cheered wildly as the Australian Open champion Sabalenka sent one into the net on match point.
The win kept alive a hot streak for Swiatek, who won the China Open last month.
"Thank you guys for coming. Thank you for cheering. I really appreciate it. You give us energy to play from December to November. I'm really grateful. See you tomorrow," Swiatek told the crowd after the match.
She faces a tough challenge against an in-form Pegula, who shredded US Open champion Coco Gauff 6-2, 6-1 to reach the title match on Saturday.
"Jessie (Pegula) is a great player, and she fully deserves to be in the final of any tournament," Swiatek said. "I know it's not going to be easy.
"There's a lot to think about. I'm just going to focus on myself tomorrow. She's really solid and can handle everything mentally. I'll try to do my best and give 100%. That's all I can do."
Neither finalist has dropped a set so far in Cancun. Pegula beat Swiatek in their last meeting in the Montreal semi-final.