Liverpool fans have mocked Manchester United by flying a banner which read "6x European champions" above Perth's WACA stadium during an open training session for Ole Gunnar Solskjaer's side.
Liverpool, the most successful British side in European competitions, won a sixth title with Champions League victory over Tottenham at the end of last season.
United are currently in Australia as part of their pre-season tour and face Perth Glory in a friendly on Saturday before taking on Leeds next week.
Banner-baiting between the two sides has long been part of the rivalry between both sets of fans, with Liverpool supporters revealing a "Come Back When You Have Won 18" banner back in 1994.
United then responded with banners marking both their 18th league title in 2008-09 as well as one for their 19th during an Anfield encounter in October 2011 which saw their number of league title surpass Liverpool's total.