Manchester United legend Ruud van Nistelrooy has urged PSV Eindhoven players to ignore the crowd tonight.
PSV are at Old Trafford to face United.
Van Nistelrooy, a veteran of United and PSV, told De Telegraaf: "On Wednesday the PSV players will experience what it is like to play at a packed Old Trafford.
"You have on one side the enjoyment, but on the other hand you must make sure you offer a top performance. Finding the right blend is quite difficult.
"When you're there, you get intimidated.
"You must guard against this - otherwise it becomes a big problem."