Shrewsbury boss Micky Mellon believes his side must execute their plan perfectly to beat Manchester United.
The Shrews host United for the first time in their history in Monday's FA Cup fifth-round clash.
Louis van Gaal is under increasing pressure and defeat to the Sky Bet League One side will turn up the heat on the Dutchman and see him pushed closer to the exit door.
Shrewsbury lost 2-1 to Chelsea in last season's League Cup after giving them a scare and Mellon knows how they can stun United.
Shrewsbury only lost to Chelsea last season after a late Jermaine Grandison own goal and Mellon wants them to approach the United game in the same fearless way.