Rooney injured his ankle in the final minute of Tuesday's match in Munich
By Alan Hansen
BBC Sport football expert
Wayne Rooney's ankle injury has tilted the balance of Saturday's Premier League "title decider" between Manchester United and Chelsea at Old Trafford back towards Carlo Ancelotti's team.
It is always dangerous to attach too much significance to one game, especially given the twists and turns of this season, but I believe that if the home side can deliver a victory, it will ultimately result in a fourth successive Premier League crown for Sir Alex Ferguson's side.
But disappointingly for United, Rooney's injury - sustained late in the Champions League defeat against Bayern Munich - has inevitably reduced their chances of getting that potentially decisive win.
I would have called the game "60-40" in United's favour had Rooney been fit. I would now change those odds to "50-50" - that is how vital I believe he has become to United's cause.
Rooney's absence will have a massive impact on United. Not only is he their best player, but he has carried them this season whenever they have had a bad time. He has won match after match, while his goal return - 34 this season for United - has been phenomenal.
Had Jose Mourinho still been manager of the Blues, this title race would have been over with five games to go and the trophy on its way to Stamford Bridge
His injury will also have an impact on the atmosphere in the Chelsea dressing room. John Terry and co will get a huge lift in confidence.
I have spoken before about how the absence of the opposition's main player can galvanise a team. Some say it does not matter. Let me tell you it does. Absolutely.
Rooney's influence on the game, his energy levels and ability will be missed by United. How can they not be?
United are not exactly impoverished in their resources and can bring in quality players like Dimitar Berbatov, but none of the possible replacements is Rooney. Berbatov is a very good player, but will he harass and hound the Chelsea defenders like his team-mate?
Rooney is so clever in his play and is always up to something. Like Ian Rush, a former team-mate of mine, he is a striker who can get into the heads of defenders and be the catalyst for uncertainty.
As a former central defender myself, I can confidently state that Terry and Alex will be sleeping a lot more soundly on Friday night now Rooney is not playing.
But the fact that Rooney is missing does not mean Manchester United cannot win. If they do win, then they will stretch their lead to four points with only five games left. It then becomes very hard for Chelsea to catch up.
So while this game is not quite a "must win" for Chelsea, you can place it firmly in the category of "must not lose". The onus is on them to ensure they get a positive result, preferably a victory, at the home of the champions.
Chelsea have had the luxury, if you can call it that, of being freed from the pressures of Champions League football.
Ancelotti believes his side may benefit from the extra time to prepare for Saturday's game. But, make no mistake, if you asked anyone at Stamford Bridge whether they wanted a free week or a Champions League quarter-final, it would be the latter every time.
As a player you do not fear tired legs when chasing major trophies at the crunch end of the season. The adrenalin carries you through.
It surprises me that United are in prime position to win the title, having never seen a team play so badly so often as they did earlier in the season and still remain in the hunt for silverware.
In some ways, that's down to Chelsea and Arsenal, who have been inconsistent. Had Jose Mourinho still been manager of the Blues, this title race would have been over with five games to go and the trophy on its way to Stamford Bridge.
As for Arsenal, I have never thought they were going to win the title and still regard them as rank outsiders. The real duel is between United and Chelsea.
Berbatov will have to shoulder more responsibility in Rooney's absence
Chelsea were magnificent on Saturday when they scored seven against Aston Villa. They also scored seven against Sunderland and have recorded other big wins at Stamford Bridge. But they have also been woeful on their travels on occasions.
I was critical of them after they only drew at Blackburn after taking a 1-0 lead. Titles can be decided by fine margins, so they should have been desperate to press home the opportunity they created for themselves at Ewood Park.
It will be a very different scenario at Old Trafford. The pressure is on Chelsea not to lose - and in reality they need to win.
United will approach the game as they always do, with caution at the back and a devastating ability to score goals on the counter-attack. And when it comes to the big games, they have a habit of doing enough to win, even when they are not at their best.
I would certainly prefer to be in United's position going into the match, which is one everyone will be looking forward to.
Sadly, a player fit to grace any big football occasion will be reduced to the role of spectator.
Alan Hansen was talking to BBC Sport's Phil McNulty.
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