Australian Open: Serena, Kerber struggle for form

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Such is the form of the world's top-ranked players, the Australian Open women's draw shapes as being wide open.

Slowly is perhaps the best way to describe how many of the top 10 have begun the season.

For the most part, losses have been against lesser opponents.

Starting from the top, with world number one Angelique Kerber.

The German won one of her three lead-up matches, and even then she was pushed to three sets to beat Ashleigh Barty - a talented Australian but the world number 232.

Serena Williams won her opener in Auckland before committing an astonishing 88 unforced errors in a second-round loss.

World number four Simona Halep opted for Shenzhen to start her year, losing to eventual champion Katerina Siniakova - also in the second round.

Garbine Muguruza somehow scratched her way to the Brisbane International semi-finals before retiring with a thigh injury.

Grand slams, however, are different stages, especially for Williams.

The 22-time major champion has reached at least the semi-finals at every grand slam in the past two years.

Like Kerber, Williams may find some early rhythm in matches she should win in the first week.

But winning form is good form.

Kerber reached the final in Brisbane last year before winning the title at Melbourne Park. In 2015, Williams chose the Hopman Cup as her lead-up, helping the United States to the final.

Li Na won Shenzhen, then the Australian Open, in 2014. Victoria Azarenka reached the semis in Brisbane in 2013, and won Sydney in 2012.

Even going further back - Kim Clijsters was a finalist in Sydney in 2011, as was Serena in 2010.

It may leave the door open for a potential first-time grand-slam winner.

World number three Agnieszka Radwanska may have switched racquets, but the Pole made the last eight in Shenzhen and showed good form in Sydney.

Perhaps the most dangerous player is Karolina Pliskova, the powerful Czech who was runner-up at last year's US Open.

She claimed the title in Brisbane in style, dropping just one set for the tournament and only nine games in total in her semi and final wins.

The year is young, but winning form is needed heading to Melbourne.