However, United striker Oli McBurnie believes his Blades team will be up for the game.
"It doesn't get any easier, but it's what we live for," the striker told SUTV.
"It's why we're in the best league in the world. It's why we worked so hard last year. We could've chucked it all them times when people thought we were going to chuck it, stayed in the Championship and have an easy life. We don't want to do that, we want to play against the best teams in the world.
"Everything going on has kind of made me enjoy it again, and have that enjoyment of going into these battles. What is there to fear? There's no pressure, so go and enjoy playing at these big stadiums and upset a few people. Everyone thinks we're the worst team in Premier League history, so go and show we're not that."