Serena beats Ivanovic in WTA Finals opener

Serena Williams won her opening match at the WTA Finals on Monday, beating Ana Ivanovic 6-4, 6-4 in the Red Group for her 16th consecutive victory at the season-ending tournament.

Williams came into the finals after injuries forced her out of her previous two outings and following Russian official Shamil Tarpischev's disparaging comments about her and sister Venus.

The top-ranked American hit 12 aces against Ivanovic, improving her career record against the Serb to 8-1.

Williams has not lost at the WTA Finals since 2011.