TENNIS: It's official - two-time Australian Open champion Victoria Azarenka has withdrawn from the year's first grand slam.

Tournament officials on Monday morning confirmed that the former top-ranked Belarusian will not compete at Melbourne Park next week.

"It's unfortunate that (Azarenka) is unable to travel to Australia this year. The Australian Open is her favourite tournament and she's looking forward to returning to Melbourne next year," tournament director Craig Tiley said.

She had been granted a wildcard to the event but has been in doubt in recent weeks due to her ongoing custody dispute with her former partner over her infant son Leo.

Azarenka not played since Wimbledon in July because she cannot leave California with her son until a dispute with her former partner ends.

Croatian-Australian Ajla Tomljanovic, who recently played in the Brisbane International, has been awarded Azarenka's discretionary wildcard.

Meanwhile, 2008 champion Maria Sharapova has been put through her paces at Melbourne Park on Monday.

The former world No.1 is usually seen in the more familiar surroundings of Rod Laver Arena but took to Showcourt 3 under the watchful eye of coach Sven Groeneveld, working extensively on her ground strokes for lengthy periods.

The star missed last year's tournament due to suspension and is rated an $11 chance to win the Australian Open.