Maria Sharapova has been slammed by tennis fans after taking a lengthy bathroom break in her fourth round loss to Australia's Ash Barty.

After claiming the first set 6-4, the Russian lost the second 1-6 then exited the court to head to the bathroom.

She was gone for some time and was greeted by a raucous boos from the Rod Laver Arena crowd when finally emerged and ran back on to the court.

Sharapova was then booed again by some sections of the crowd, despite the bathroom break being within the rules, as she took her place on the baseline for the first point of the deciding set.

Some fans believe the move was tactical, to throw Barty off her game after she gathered serious momentum, and labelled it "terrible sportsmanship".

If it was, it didn't work. Barty stormed to a 4-0 lead in the deciding set before taking it 6-4 to win the match and advance to the quarter-finals.