Cheeky: Venus appeared to have a bare behind at the Australian Open

Unflattering: The flesh-coloured shorts did Venus no favours

The 29-year-old attracted plenty of wolf-whistles for the risque outfit, which brought to mind the famous Athena ‘Tennis Girl’ poster of model Fiona Butler scratching her naked bottom that once adorned the walls of so many teenage boys’ bedrooms.

Williams revealed that she designed the eye-catching outfit herself, apparently managing to circumvent the Melbourne tournament’s ban on skimpy outfits.

The bright yellow dress also boasted a flesh-coloured panel at the front, making it appear to have a plunging neckline.

A real eyeful: Venus said the knickers showed her outfit to its best advantage

Low cut: The dress had a flesh-coloured panel on the front to give the illusion it was daringly low

Looking back: The Athena ‘Tennis Girl’ poste

Williams’s outfit attracted a great deal of speculation on the internet, with dozens of fans asking her via the Twitter social networking site if she had ‘gone commando’ – or worn no underwear – on court.

She explained to fans: ‘My dress for the Australian Open has been one of my best designs ever! It’s all about the slits and V-neck. I am wearing undershorts the same colour as my skin, so it gives the slits in my dress the full effect!’

She added: ‘This is completely my design. I just sketched it out. The whole idea is just about the illusion that I’m wearing a deep V-neck. Then the idea was to wear shorts that were like the same colour as my skin. It works very well, apparently.

‘This is completely my design. Anything I wear on the court probably you could wear 20 years from now.’

Williams recently completed a fashion degree while on tour, and has launched her own clothing line called EleVen and interior design company, VStarr.

The extra attention did nothing to distract the American from her third round match against Australian Casey Dellacqua, which she won comfortably in two sets .

Last year, the Australian Open introduced a ban on daring dresses after French player Alize Cornet wore a see-through top during another match in Australia.

The Williams sisters have often attracted attention for their outfits, with Serena wearing a black catsuit for the 2002 US Open.