Sir Alex Ferguson has questioned the legitimacy of Arsenal's "lilywhite" image ahead of their game at Manchester United tomorrow night, citing their disciplinary record as evidence that Arsène Wenger has nurtured his most competitive side "since the days of Martin Keown".

Ferguson expects a match of the "usual feisty nature" when the two old adversaries meet at Old Trafford and, writing in his programme notes, he questioned whether Wenger had deliberately perpetuated the sense that Arsenal were football purists.

"Our matches with Arsenal have always been competitive and don't be deceived by the popular view that the Gunners play pretty football but can be kicked out of games," Ferguson writes.

"Arsène has possibly encouraged this because earlier in the season he was berating two or three teams for being overly physical in their games against his side. I'm sure he saw it that way, but other managers and coaches tell me the present Arsenal side are one of the toughest in the Premier League, and the most physical since the days of Martin Keown.

"They play nice football and weave some intricate patterns but there is an edge through their team that also accounts for their presence as title challengers this season. His boys are not the lilywhites portrayed by their admirers. How many players have they had sent off this season? Three: Laurent Koscielny [twice], Jack Wilshere and Alex Song."

Ferguson's comments are about as provocative as it gets these days between himself and Wenger now that the two men, once sworn enemies, have called a truce to their feud. United's manager used to complain that Wenger would never have a drink with him after matches, but that has changed over the past couple of seasons.

"When he first came to England, Arsène didn't totally embrace the tradition but I am happy to say he regularly comes into my office for a glass of wine after a match and, of course, he entertains at the Emirates."

Ferguson also keeps to his promise to ask United's supporters to refrain from targeting Wenger with the offensive songs that have led to complaints over recent years.

"Before we get under way could I make a special appeal to that small section of our fans who seem to get perverse pleasure from taunting Arsène Wenger with crude chants? He deserves better, much better."