Roberto Martínez has masterminded a mini-recovery at Wigan over the past few weeks, with back-to-back away wins at Sunderland and West Bromwich Albion followed by highly creditable home draws against Chelsea and Liverpool, but the Wigan Athletic manager does not need reminding that Old Trafford on Boxing Day represents the toughest challenge of all.

No Wigan manager would. The Latics have never taken so much as a point from Manchester United in all their years of trying across their seven seasons in the Premier League. They have either beaten or held every other team in the league but in their last 13 encounters with United, including the 2006 Carling Cup final, a goal tally of 43 conceded to four scored makes for sorry reading – even to Martínez, who has been in charge only since 2009 but noted at Fulham on Wednesday that not only do United appear to be returning to their best but Wayne Rooney is running into form.

"The next game is about as big a test as anyone could get," Martínez said. "What you can guarantee from United is that they know when to peak. They know how to be strong at the right moment. December is a month when you see the big players performing so it's not really a surprise that Wayne is hitting form at just the right time. He is a very special player, one of the most influential individuals any team could have, but it would be a big mistake from our point of view just to focus on him.

"If we do that, then we risk giving extra space to Nani, Berbatov, Giggs and all the other players that can hurt us. But Wayne is a unique type of player. He can get you a goal from nothing or he can score a goal in a moment when the team is not doing too well, and players like that are invaluable. We have to work hard as a team for all our goals and we have not been scoring enough but, when you have a player who can score a goal to change a game, it can make a real difference."

Martínez is aware that this could be considered a good time to be playing United, with Nemanja Vidic, Tom Cleverley and Ashley Young unavailable and Rio Ferdinand and Phil Jones doubtful, but believes the 5-0 result at Craven Cottage indicated otherwise.

"In my opinion a top team like United are never really weakened by injuries and suspensions, not in normal circumstances anyway," he said. "Not in the way that smaller clubs often can be. United have a Champions League squad and a great tradition. Whoever represents them is ready to play at the required level and, even if it is a reserve player who has been waiting for his chance, he will be hungry and fresh and ready for the opportunity.

"When you look at the result at Fulham, even considering their injuries I think it would be a mistake to underestimate United. If you ask me, they still deserve to be considered as favourites for the title. Manchester City have a great chance this season, don't get me wrong. I think Roberto Mancini has put together a great team. But United have all the experience and that could be important."