Serena Williams has cruised to a straight-sets win in her second match of the WTA Championships, beating Agnieszka Radwanska 6-2 6-4.
The Pole made a promising starting, forcing the world number one to save a break point in the opening game of the first set, but the American soon took control, overpowering the third seed to clinch to breaks.
Williams looked to be in charge in the second, charging to a 3-1 lead, but some patient play from Radwanska allowed her to level the scores.
The next three games went with serve before some attacking tennis from the top seed earned her two match points, and she clinched it on the second to secure the win.
