Ferguson: Arsenal clash biggest test to date
United are in second place with 50 points while Arsenal are just one point and one place behind. Chelsea are top with 51 points and have played one game less than both their rivals.
"I think the game on Sunday, to my mind now looking at the way the league is shaping up, is the biggest game of the season for us," Ferguson told reporters on Friday.
"Arsenal have gone on a consistent run and it's amazing how this league has changed.
"The team that is most consistent will win the league now and Arsenal's current form has been very good and I'm looking forward to it."
Ferguson called on United's supporters to avoid abusing Arsenal manager Arsene Wenger. In the past, Wenger has been the subject of intense vitriol from United fans but Ferguson does not want to see or hear a repeat of that.
"Sometimes I can't hear these chants and I can't make them out but I know there's been some terrible abuse from our fans to Arsene Wenger," Ferguson said.
"There must be a line drawn and I think our fans must know that themselves."
Ferguson said United are unlikely to appeal against the four match ban defender Rio Ferdinand must now serve for a violent conduct charge.
The England international was spotted flooring Craig Fagan in last weekend's 4-0 win over Hull City and originally received a three-match punishment, but after challenging the decision, the FA not only knocked back his appeal but added another game as well for "a frivolous" appeal.