The Potters entertain the Premier League leaders today.
Pulis said: “If United play to their maximum they can beat any team in the world and I include Barcelona in that. I’ve watched the tapes and they are frightening.
“If you factor in that Wayne Rooney is in the form of his life, it’s daunting. But will try and make it as difficult as we can. Not many teams look forward to coming to the Britannia Stadium with 28,000 people breathing down their necks.”