WTA Finals Preview, Day 4: Pliskova vs. Sveta, Aga vs. Muguruza

Radwanska and Muguruza desperately need wins in their second round-robin matches. 

Tie Break Tens showed that tennis shouldn't be afraid to experiment

Alternative formats are trying to cut some of the fat from the sport. 

WATCH: Madison Keys hits brilliant winner in maiden WTA Finals victory

Keys beat Cibulkova, 6-1, 6-4, to improve to 1-1 in the Red Group. 

Elina Svitolina complains of online abuse from Russians in Moscow

"It was a very tough tournament, and I don't think I will come back," she said. 

Kuznetsova chops hair, cuts down No. 3 Radwanska in WTA Finals stunner

Sveta, who barely made the cut for Singapore, beat the world No. 3 in 2:48, 7-5, 1-6, 7-5.

Tennis Podcast

Final Thoughts on Kyrgios; First Look at WTA Finals

Steve Tignor and Ed McGrogan dig into a busy week of tennis news, on and off the court.