It took Louis van Gaal less than a minute of his weekly press conference to burst Manchester United's bubble and re-open some of the more troubling issues of his time in charge at Old Trafford. The Dutchman wasted no time in revealing that Michael Carrick, Daley Blind, Phil Jones and Marcos Rojo will miss the much-anticipated clash with Chelsea at Stamford Bridge through injury. Four players capable of filling two key positions. 'The worst scenario,' Van Gaal called it. Wayne Rooney arrives in London ahead of the Chelsea clash while Ashley Young (right) poses with a fan . Manchester United captain Wayne Rooney could be dropped further back into midfield against Chelsea . Rooney had been impressing for the Red Devils in his favoured striking role but United have players out . Michael Carrick (left) limped off against Manchester City while Marcos Rojo (right) picked up an injury too . Daley Blind (left) and Phil Jones (right) are also out injured for United ahead of their game with Chelsea . United midfielder Juan Mata posts a picture on his official Instagram of the squad's journey to London . United boss Louis van Gaal (left) and assistant Ryan Giggs (right) carry their luggage on Friday . Van Gaal puts his arm around Rooney during a training session earlier this week ahead of Saturday's game . The uplifting victory in last weekend's Manchester derby has come at a price. All of a sudden, United's chances of extending an impressive run of six straight Premier League wins by becoming the first top-flight team to win away at Chelsea this season look decidedly slimmer. Van Gaal must take on his old apprentice Jose Mourinho without either of his two first-choice holding midfielders, Carrick and Blind, and two senior centre-backs in Jones and Rojo. Blind was hurt in the Manchester derby by a challenge from City skipper Vincent Kompany. It means that captain Wayne Rooney is likely to be asked to sacrifice himself for the team once again by dropping into midfield — an issue that both player and manager must have hoped was behind them. With Robin van Persie not ready to return from injury, that in turn raises the old question about whether Radamel Falcao has the necessary match sharpness to replace Rooney and lead United's attack having not started a game since February. United striker Robin van Persie has not yet been passed fit enough to return to first-team action . There remain doubts over Radamel Falcao's ability to fill the void in United's attack against Chelsea . Luke Shaw is set to take over from Blind at left back despite fitness concerns that have plagued him since his £28million move from Southampton last summer and led to him being hooked at half-time in the FA Cup defeat by Arsenal last month, not to be seen since. And then there's the likely choice of replacement for Rojo between Tyler Blackett and Paddy McNair, two young defenders who have not featured since January and February respectively. Both figured more prominently in the first half of the season when persistent injury problems and experimental formations slowed Van Gaal's progress. We were back on familiar ground on Friday, the fragility of United's squad all too apparent. Was he concerned by the lack of playing time among the players he may turn to? The United boss answered with one of his Dutch sayings. 'Yes, but that's also a truth like a cow,' he said. 'It means a rhetorical question. You know the answer already. 'There is more balance in the team because I have played the same line-up more. Luke Shaw (left) looks set to return to the United first-team, while Rooney will drop into midfield . 'I didn't have injuries anymore and now, coincidentally, we have four in two positions where we don't have any other players. That's difficult. 'It's the worst scenario because Rojo and Jones are good players at the left central defender position. Jonny Evans is suspended so we don't have many choices. 'Luke Shaw has already had more than four or five weeks with no match and I don't like that. But we train and I think he is fit enough. 'Blind and Carrick could play the midfield holding position and I don't have any other option, or I have to play Wayne Rooney in that position again. I have to puzzle a lot.' With Chelsea holding an eight-point lead and a game in hand over United, Van Gaal is experienced enough to know that even victory is unlikely to make any difference in the title race. 'It's still possible, I've said that before, but it is not logical,' he added. 'It's more when and if, and I don't believe in when and if. I believe in facts. The fact is that we are behind Chelsea. 'But, all right, we have to play against them and so do Arsenal so we can lay pressure on Chelsea's shoulders. You never know, you've seen it in previous Premier League seasons. 'They play at home but I think that Chelsea will be satisfied with a draw.' United midfielder Mata (right) gets ready to play a pass during a club training session on Friday . Van Gaal, meanwhile, will be satisfied if United hold on to third place and fulfil his primary aim of qualification for the Champions League. But he made it clear that first place is ultimately all that matters and what drives him on at the age of 63 when financial security is no longer an issue. 'We live for these titles,' he said. 'We are doing this for that. The only satisfaction you have as a manager is when you win a title. 'When you are second or third you can play Champions League, but a title is more fixed and you have your name on it. That's why managers are fixated on titles. When you reach that goal you are happy. 'To be involved in the game with young people to reach a goal, that is why I'm still a manager because I don't have to work any more — you can count on that.'
Manchester United are missing four players in key positions ahead of the crucial Premier League game with title rivals Chelsea at Stamford Bridge .
Daley Blind, Michael Carrick, Phil Jones and Marcos Rojo are all out injured .
Wayne Rooney could be dropped deeper into midfield to compensate .
The decision to play Rooney in midfield has been an unpopular one before .