Mischievous Liverpool supporters in Australia have flown a banner over Manchester United's open training session at the WACA in Perth.
The plane cruised over Ole Gunnar Solskjaer's squad trailing the message: 'Liverpool FC - 6 X EUROPEAN CHAMPIONS.'
Jurgen Klopp's side have huge support down under and made their presence felt with a dig at their rivals, who had 12,000 fans watching training and the provocative banner above them.
It is unknown whether the small white aircraft was hired by one fan or a group of supporters.
But they timed the prank to perfection with the United players working hard on the famous cricket ground's turf below.
The Old Trafford club endured a dreadful campaign last season, a stark contrast to their old rivals who ran Manchester City close in the Premier League and then capped off their campaign with their sixth European Cup.
No doubt it was an untimely reminder for Solskjaer and Co, although perhaps it motivated them to push harder in their pre-season session.
A crowd of 12,000 turned up at the WACA to see Solskjaer put his squad through their second double training session in three days on tour under the floodlights at the famous cricket venue. United face Perth Glory at the nearby Optus Stadium at the weekend and Leeds United next week.
Romelu Lukaku, heavily linked with a move to Inter Milan, and Anthony Martial did not take part in the workout but United said they were doing alternative gym based training instead.
Solskjaer is determined to get his players fit after criticising their conditioning after he succeeded Jose Mourinho in December.
The United manager admits that travelling to Australia, Singapore and China after just a week's training at Carrington could take its toll on the squad, but believes that is part and parcel of playing for United.
'I think the boys have done well in the sessions we've done,' he said. 'Of course if you're at Carrington working in your normal environment sometimes that goes stale.
'Sometimes when go away you get new enthusiasm, energy and coming here, yes we know it's a long way to go, but that's part of being at Man Utd. We are the biggest club in the world, we do have supporters all around the world.
'I'm used to it, I played here for 11 years, I'm used to that pre-season. It's going to be hard, when we come back we might have a bit of jet lag, but I talked about robustness and you've got to get over it, that's how it is at the top.'