Serena Williams and her nearest rival, Victoria Azarenka, differed in opinion and quality of performance in taking their first steps toward a much hoped-for meeting in Sunday's final at the WTA Championships on Tuesday.

Williams crushed one of the few women to have beaten her in the past 15 months as she began defense of the title with a speedily impressive win.

The world No 1 took little more than an hour to win 6-3, 6-1 against Angelique Kerber, the German who defeated her in Cincinnati last year but who this time was outplayed from the moment she dropped serve in her opening service game.