Istanbul, Turkey (SportsNetwork.com) - Reigning champion Serena Williams and former world No. 1 star Victoria Azarenka were a pair of opening-day winners at the season-ending WTA Championships in Istanbul.
The top-seeded Williams, who will finish as the year-end No. 1 for the third time in her career, waltzed past eighth-seeded German left-hander Angelique Kerber 6-3, 6-1 in 64 minutes on the indoor hardcourt at Sinan Erdem Dome on Tuesday.
This week's four-woman Red Group is led by the U.S. and French Open champion Williams (1-0) and also includes third-seeded Agnieszka Radwanska, fifth- seeded 2011 titlist Petra Kvitova and Kerber (0-1).
The three-time Championships titlist and two-time runner-up Williams beat Maria Sharapova in last year's finale in Turkey.
Meanwhile, the second-seeded Azarenka got past sixth-seeded Italian Sara Errani 7-6 (7-4), 6-2. The Australian Open champion Azarenka was down a pair of breaks, trailing 2-5 in he first set, before charging back to handle the former French Open runner-up Errani. The first set took 1 hour, 27 minutes to complete.
The 2011 Championships runner-up Azarenka (1-0) spearheads this week's four- player White Group, which also features Errani (0-1), fourth-seeded Aussie Open runner-up Li Na and seventh-seeded Jelena Jankovic.
Istanbul is hosting this elite eight-woman event for a third and final time before it shifts to Singapore next year.
Round-robin play will be staged Tuesday through Friday, followed by semifinal action on Saturday, and a lucrative final on Sunday.