Madison Keys has announced that she will not be participating in the WTA finals due to illness before her final round-robin clash against Elena Rybakina.
Rybakina, who is already through to the semi-finals as the group winner, will instead play second alternative Ekaterina Alexandrova.
The Australian Open champion suffered two defeats in round-robin play this week in Riyadh, to Iga Swiatek and Amanda Anisimova, and had no chance of advancing to Friday's semi-finals.
"I'm really disappointed to not be feeling my best and ultimately having to withdraw from the tournament. It's a huge accomplishment to make it this far and I'm very proud of myself for doing that and having a great year. I hope to be back next year," said the 30-year-old in an official statement.
Alexandrova is the second alternate in Riyadh. The first alternate, Mirra Andreeva, decided to not sign in due to not being fit to play on Wednesday and still being involved in the doubles at the WTA Finals.
On Monday, Keys indicated that she's unwell when she avoided shaking hands with Anisimova, gesturing that she did not want to pass it on.
Besides that, Jasmine Paolini is reportedly also struggling with illness at the WTA Finals, with the Italian knocked out of the singles but still involved in the doubles along with Sara Errani.
Wednesday's schedule features the third and final set of round-robin matches in the Serena Williams Group, with Rybakina taking on Alexandrova and Swiatek facing off with Anisimova.
