MANCHESTER UNITED fans believe Thomas Muller “isn’t taking them seriously” after his bizarre antics in training.

Erik ten Hag’s side face Bayern Munich at the Allianz Arena in their Champions League opener on Wednesday night.

Thomas Muller was being the joker again as Bayern Munich trained ahead of facing Man Utd

The veteran bizarrely jumped along the side of the pitch

As Man Utd players knuckled down in training at Carrington after a dressing room bust-up following their 3-1 loss to Brighton, Muller was in the mood to have a laugh.

He bizarrely jumped alongside the German team’s training pitch and pretended he had wings.

Muller’s antics have left fans in hysterics, one said: “He can’t take Man Utd seriously.”

Another added: “The funniest guy in the history of the game.”

A third commented: “That is adequate preparation for United.”

Muller is in such a jovial mood that he admitted he has been joking about Man Utd ahead of Wednesday’s game.

He said in a press conference: “One thing I learned, never underestimate Manchester United at their lowest point.

“I made some jokes earlier in training today but deep down I know it’s not looking good.”

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Muller, who owns a horse named Dave, frequently plays the clown for Bayern and has been seen throwing beer over spectators’ heads during championship celebrations.

In order to escape being questioned by reporters at an airport, the 34-year-old once feigned that his passport was his phone.

As well as calling Robert Lewandowski, a former Bayern striker, “LewanGOALski” in press interviews.