World number five Jessica Pegula defeated Greece’s Maria Sakkari in straight sets 6-3 6-2 in the WTA Finals, continuing her unbeaten run through the group stages.
Pegula had already secured her spot in Saturday’s semi-finals by beating both Sabalenka and Rybakina in her earlier matches in Mexico.
But the American is yet to drop a set so far this tournament and it took her just under 80 minutes to beat Sakkari, who failed to qualify for the semi-finals after losing all of her games.
Meanwhile, fighting for a spot in the semi-finals, world number one Aryna Sabalenka and world number four Elena Rybakina had their match suspended due to wet weather.
Sabalenka won the first set 6-2 in the Australian Open final rematch on a rain interrupted evening and had Rybakina on the ropes early in the second set.
But Rybakina fought back to take the lead 5-3 before the match was called off for the night, with play to resume on Friday.
Also on Friday, Iga Swiatek will take on Ons Jabeur while Coco Gauff plays Wimbledon champion Marketa Vondrousova to decide who makes the semi-finals.
