DOHA, Qatar — Serena Williams will play big sister Venus in the final of the Sony Ericsson Championships.

Serena advanced to Sunday’s title match when Caroline Wozniacki retired with an apparent abdominal injury while trailing 6-4, 0-1. Wozniacki received medical treatment in the first set and quit after breaking Williams to start the second.
The 19-year-old Dane has been struggling with injuries all week and said Friday her aching abdominal muscles were affecting her serve.
Earlier, Venus Williams advanced to her second straight final in this event by rallying past Jelena Jankovic 5-7, 6-3, 6-4.