Sir Alex Ferguson says Manchester United face an "injury crisis of major proportions" after Rio Ferdinand went off injured against Middlesbrough.
Ferdinand limped off at half-time against Boro
The defender will be out for two weeks after suffering a recurrence of a groin injury during United's 1-1 home draw.
Ferdinand will miss the Champions League semi-final against AC Milan on Tuesday but might return for the vital Premiership game with Chelsea on 9 May.
"I'm only playing with 12 players now, the rest are injured," said Ferguson.
"It's an injury crisis of major proportions. We've got to patch up a team for this massive game on Tuesday now."
Ferdinand joined defender Nemanja Vidic (collarbone), captain Gary Neville (ankle), midfielder Park Ji-sung (knee) and forward Louis Saha (hamstring) on the sidelines.
Kieran Richardson is also an injury doubt after going off at half-time against Middlesbrough after scoring United's goal.
United, whose Premiership lead could be cut to one point if Chelsea win at Newcastle on Sunday, face a crucial few weeks as they chase three trophies.
The game at Chelsea was always going to be critical and the door is open to them now
Ferguson blamed Ferdinand's injury for Boro's equalising goal, saying the England defender was physicially unable to stop Mark Viduka heading home on the stroke of half-time.
"The injuries killed us in the first half. I was hoping to get to half-time to get Rio off... Rio was limping, he just couldn't get to it," he said.
"Maybe if I'd taken him off it would have been OK."
Ferguson was worried that his side did not play to their usual standards in the second half at Old Trafford.
"We must not feel sorry for ourselves. It looked like we were a little bit in the second half but this is not a time for that," he said.
"The history of our club is that we make it hard for ourselves anyway and we are back to square one.
"The game at Chelsea was always going to be critical and the door is open to them now.
"We always knew if we made mistakes they have got the ability to come back. It is a big task now."