As if further proof was needed, Saturday's against-all-odds victory over Tottenham demonstrated just how influential a vocal Old Trafford support can be.
United roared back from two goals down to win 5-2, and Cristiano Ronaldo admitted afterwards: "The fans helped us win the game. When we are together like that, the players and the supporters, you always know the result will come."
Supporters can reprise Saturday's baying din on Wednesday evening, when the reigning European champions look to reach a second successive Champions League final at the expense of Arsenal.
As ahead of last year's unforgettable win over Barcelona at the same stage, Old Trafford will be transformed into a sea of colour pre-match, and fans are urged to arrive early to help build the anticipation around the stadium.
Fans group Stretford End Flags will have nine representatives pitch-side waving flags before the game, and are providing giant banners to be passed around the crowd.
Two mosaics will be in place for supporters to hold as the teams take to the field, while fans are also urged to bring scarves, flags and, naturally, singing voices as the champions of Europe look to take a huge step towards this year's final in Rome.