Sir Alex Ferguson is urging United supporters attending the Barcelona home game on Tuesday 29 April to make Old Trafford a 'sea of red and white.'
The boss wants fans to help add Barcelona 2008 to the likes of Porto '77, Barca '84, Inter '99 and Roma '07 on the list of great European atmospheres.
Sir Alex told us: â€œThere have been so many occasions over the years of the crowd being the 12th man in the way the supporters create such great encouragement.
â€œIf our supporters bring scarves on the night it should be fantastic. We want to make sure it's a real sea of red. If we do that we have a big, big chance [of reaching the final]."
So let's show our colours, strain our vocal cords and roar the lads to Moscow.