Roy Hodgson fears Jamie Carragher dislocated his shoulder during Sunday's 2-1 Barclays Premier League defeat to Tottenham Hotspur.
Liverpool's No.23 will have the injury further assessed at Melwood on Monday.
"We think Jamie has disclocated his shoulder which is a real blow for us and for him," Hodgson told his post-match press conference.
"I don't know at this stage how long Jamie will be out for but I would think it will be quite long because it's a serious injury.
"It is a blow for us. Agger is still out injured and we are not really that well blessed for centre-halves.
"We are now without Steven Gerrard and Jamie for a period of time - both of whom are the lifeblood of this club."
SOURCE Liverpool have been drawn away to Manchester United in the third round of the FA Cup.
The Reds will travel to Old Trafford on the weekend of January 8/9 in the only all-Barclays Premier League tie of the round.
The two sides last met in the FA Cup at the fifth round stage of the competition in the 2005-06 season. Peter Crouch's first-half goal gave Liverpool a 1-0 victory that afternoon en route to the Reds lifting the trophy in Cardiff.
Burnley v Port Vale
Coventry City v Crystal Palace
Bristol City v Sheffield Wednesday
Fulham v Peterborough United
Doncaster Rovers v Wolverhampton Wanderers
Brighton & Hove Albion or FC United of Manchester v Portsmouth
Huddersfield Town v Dover Athletic
Crawley Town or Swindon Town v Derby County
West Ham United v Barnsley
Reading v West Bromwich Albion
Arsenal v Leeds United
Sheffield United v Aston Villa
Leicester City v Manchester City
Bolton Wanderers v York City
Blackburn Rovers v Queens Park Rangers
Swansea City v Colchester United
Wycombe Wanderers v Hereford United or Lincoln City
Stevenage v Newcastle United
Burton Albion v Middlesbrough
Millwall v Birmingham City
Southampton v Blackpool
Watford v Hartlepool United or Yeovil Town
Chelsea v Ipswich Town
Sunderland v Notts County or AFC Bournemouth
Scunthorpe United v Everton
Manchester United v Liverpool
Hull City v Wigan Athletic
Stoke City v Cardiff City
Tottenham Hotspur v Charlton Athletic or Luton Town
Preston North End v Nottingham Forest
Norwich City v Droylsden or Leyton Orient
Torquay United v Carlisle United
SOURCE WHY MUST THE FOOTBALL GODS LOVE US FOR A SECOND, THEN HATE US THE NEXT?! UGH. DAMNIT. Although I think we'll win against Man Utd, this Carra injury is KILLING me. Our defense without Carra is just. Not as good. OY.