Louis van Gaal believes Arsenal, who United are ready to face, are on a different level than any other team in the EPL.
Arsenal are third and looking to close the five-point gap between them and leaders Leicester City.
Buy United need record a positive win to maintain the path to UCL qualification.
However, their Dutch boss feels Arsenal will be particularly difficult to beat, citing October’s comprehensive defeat in the build-up to the clash, with Alexis Sanchez and Mesut Ozil combininig to put the Gunners 3-0 up inside 20 minutes.
“They were the only ones to beat us 3-0,” Van Gaal said. “They are at a different level.”
He added: “Arsenal are one of the best teams in the Premier League but Arsenal are not always consistent.
“The big challenge for us is to put in another big performance so soon after the last one. We played our European game on Thursday while Arsenal played on Tuesday, so we are not in a good position, but we will see.”
United – sixth in the table – have the opportunity to close the six-point gap to Manchester City in fourth due to their cross-city rivals’ involvement in Sunday’s League Cup Final at Wembley.