A banner flew above their training session at the WACA Ground in Perth on Thursday which read: “Liverpool FC – 6x European champions”.
Ole Gunnar Solskjaer’s side was preparing for their public session and the plane was seen circling for some time, while United players trained.
Liverpool added their sixth European crown in June when they beat Tottenham in the final in Madrid.
The club’s fans clearly are not willing to let their fierce rivals forget about the success they have enjoyed in Europe.
The Red Devils have won a mere three titles, in 1968, 1999 and 2008.
LATEST FOOTBALL NEWS
United are in Australia for their pre-season tour where they will play Perth Glory in a friendly on Saturday before taking on Leeds next week.
Try will then travel to Singapore and China before heading back to Europe ahead of the start of the Premier League season.
Striker Romelu Lukaku did not train with the squad on Thursday, which will do little to dampen speculation about his future.
Serie A side Inter are keen to add him to their squad and it is said he was doing alternative gym-based work, along with fellow forward Anthony Martial.
Meanwhile, Southampton midfielder Mario Lemina has confirmed he wants to leave the Premier League side this summer.
Linked with United and Arsenal, the player said he would be happy to join either even though they are in the Europa League and not Champions League.
“It’s a bonus. If I have the opportunity to play this season, why not, but I’m really trying to regain consistency, become an important player in a team with high goals.
“I need to play. That’s really my priority. I want to show everyone what I can do.”