World No. 1 Aryna Sabalenka fell to Elena Rybakina 6-4, 3-6, 6-1 in the WTA Finals group stage on Wednesday. Sabalenka hasn’t been eliminated from competition yet as she already clinched her group.

It was a big upset as Rybakina is coming off two months of a break from tennis. She had only played three matches since July, when she reached the semifinals of Wimbledon. This was Rybakina’s only win at the WTA Finals, meaning her run at the tournament is over despite the win.

Sabalenka’s seven-match winning streak was snapped with this loss. Her streak is carried over from winning the Wuhan Open last month.

Sabalenka officially earned the end of year No. 1 ranking on Tuesday when Iga Swiatek lost in the tournament. Sabalenka will move on to the WTA Finals semifinal on Friday in an attempt to win her first title at the tournament. It would be the perfect way to end her career-best year.