Former Arsenal striker Alan Smith has claimed that the Gunners struggle to perform to their best at Old Trafford.
The Gunners have not won at the venue since 2006, and Smith is concerned that Arsenal struggle to deal with crucial matches of this nature.
"If United let Arsenal play, the visitors are more than capable of creating chances, just as they did in November at the Emirates when the league game should have been over in the opening 20 minutes," he told The Telegraph.
"It wasn't though. And a very average United side eventually won. That is what favours Van Gaal's team here, an apparent mental block within their opponents to get the job done on occasions like this. It has been eight and a half years since Arsenal won at Old Trafford.
"For my old team at least, this is about conquering that old hurdle known as belief."
United beat Arsenal 2-1 at the Emirates Stadium when the sides last met.