Arsene Wenger's team are "not always consistent", according to the Reds Devils boss, who admits his players could find it hard to produce strong performances in successive games
Manchester United manager Louis van Gaal believes his side's upcoming opponents Arsenal are "on a different level" compared to the rest of the Premier League.
The third-placed Gunners head to Old Trafford on Sunday looking to close the five-point gap to league leaders Leicester following their title rivals 1-0 win over Crystal Palace.
United, with just one win in their last four league games, must achieve a positive result in order to maintain their challenge for a Champions League 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, Mesut Ozil and Theo Walcott all scoring within the opening 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.
- Goal