World No. 1 Aryna Sabalenka of Belarus grabbed a 6-2, 3-5 lead over fourth-ranked Elena Rybakina and boosted her chances of securing a semifinal berth at the WTA Finals in Cancun before play was suspended due to rain on Thursday night.
Sabalenka, who powered past Greek Maria Sakkari but lost to Jessica Pegula, put on a dominant performance in the first set against the big-serving Kazakh as rain caused multiple interruptions in what was a rematch of the Australian Open final.
Rybakina found her groove during the second set before play was suspended for the night in Mexico.
"Play is suspended for the night due to rain," the WTA said on X.
"The conclusion of this match and (Coco) Gauff/Pegula vs. (Laura) Siegemund/(Vera) Zvonareva will be moved to Friday's Order of Play."
Sabalenka and Iga Swiatek are in contention for the year-end number-one singles ranking. The Australian Open champion overtook the four-time major winner Swiatek and captured the top spot after the US Open.
The 25-year-old Sabalenka will retain the No. 1 spot if she goes undefeated in round-robin play or makes the final.
American Pegula booked a semifinal spot at the season-ending tournament with a 6-3, 6-2 victory over Sakkari, who came into the match knowing she was already eliminated.