Substitutes have obviously played a big role for us over the years.
Think Ole Gunnar Solskjaer at the Nou Camp in 1999. Or, indeed, Teddy Sheringham in the FA Cup final the weekend before that famous night.
Federico Macheda's impact was utterly dramatic against Aston Villa in 2009. That was his debut and numerous other Reds came off the bench to make their bow - Ryan Giggs, Eric Cantona, Robin van Persie and, more recently, Mason Greenwood are among them.
It all started with David Gaskell, still our youngest-ever player, and his shock debut in the 1956 Charity Shield against Manchester City.