All-rounder Shane Watson has insisted that Australia still have some work to do before they wrap up the third Ashes Test.

Touring England finished day four on 251-5 and must either reach a Test record 504 for victory or bat out the final three sessions to prevent the Aussies from claiming an unassailable 3-0 series lead.

"We still have a bit of work to do. The English guys batted nicely this afternoon, especially Stokesy who batted beautifully, so we have a fair amount of hard work to do in the morning," he told Sky Sports News.

"There is no doubt a nice night's sleep to freshen up will play into our hands to give it a good crack."

Watson scored 103 runs during Australia's second innings in Perth.