ISTANBUL - Serena Williams and her nearest rival Victoria Azarenka differed in opinion and quality of performance in taking first steps towards 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 last 15 months as she began her defence of the title with a speedily impressive win.

The world number one took little more than an hour to win 6-3, 6-1 against Angelique Kerber, the German who beat her in Cincinnati last year but who was now outplayed from the moment she dropped serve in her opening service game. By contrast Azarenka, appeared uncertain and care-worn, was far from consistent, and might easily have lost the first set during her 7-6 (7/4), 6-2 survival against Sara Errani, the sixth seeded Italian.

The Belarussian found it hard to force the pace and confirmed the impression of poor health given during her disappointing performances in Beijing and Tokyo. Improvement only came after squeezing through the first set tie-break. Azarenka was also ambivalent about the surface. "You know I think the court is pretty rough, I would have to say," she said frankly. "It's a little bit slow.

"But that's what we have. I think you know I can't really find excuses or something," she then rapidly qualified the remark. "If the surface can be a little bit better because it's tough on the body, maybe yeah - but I think it's the last year," she said, referring to the WTA Championships moving to Singapore next year. Williams could hardly have thought more differently. "Well you know me - you cannot ask me these questions. I will say it's fast when everyone else says it's slow," she said with nice irony. For the court to be of optimum speed it should "maybe to be faster than what it is," Williams half-agreed with Azarenka. "But I like slow surfaces, so you know, I like grass, so it doesn't matter for me," she added, appearing to offer further contradiction by suggesting grass was slow. Azarenka's difficulties also derived, she suggested, from having taken a break after a disappointing Asian swing and then returning to action in a tournament where you meet top players from the first match.

It was hard to make these adaptations during a match, Azarenka admitted, but she was helped a little by Errani, who appeared to suffer a calf injury in the second set, and gradually lost rhythm and confidence. However the world number two may need to improve if she is to win a group which includes Li Na, the Chinese player whom Azarenka only narrowly beat in the final of the Australian Open at the start of the year.

Whatever the merits of the court Williams served superbly and generated a withering power off the ground, suggesting she is as far ahead of the field as she has ever been. Neither did Petra Kvitova appear to be too bothered by the court's slowness. The 2011 champion from the Czech republic flat-hit her way to a 6-4, 6-4 win over Agnieszka Radwanska, the third-seeded former Wimbledon finalist from Poland, and now looks well placed to qualify for the semi-finals from the red group along with Williams. Later the star player came out with a star quote. Williams was asked if she could ever imagine a female champion coming from Turkey during her lifetime. "Yeah well there is a girl that....there is a champion from Compton," she said with an offbeat reference to her working class origins in Los Angeles. "So anything is possible, especially from Turkey.”