Agger injured a knee tendon in Saturday's defeat at West Brom and will not play again this campaign, while Johnson's hamstring strain in the same match will sideline him for four weeks.

Denmark international Agger has been plagued by injuries throughout his five years at Anfield; he missed the latter stages of the 2007/08 season with a foot problem, had surgery on his back the following summer and a calf injury kept him out for a couple of months this season.

"Daniel has a problem with the tendon behind his knee and won't be involved again this season," said Dalglish.

"He'll be out for a couple of months before he can start training."

With Martin Kelly's recurrence of a hamstring problem likely to keep him out for another three to four weeks it leaves Dalglish's options limited ahead of next week's visit of Manchester City.

The defence which played the final 65 minutes of the game at the Hawthorns comprised four centre-backs, with Jamie Carragher and Danny Wilson being asked to play out of position on the right and left respectively.

Fabio Aurelio's return to training after a month on the sidelines with a hamstring problem is timely but his lack of match fitness raises questions over his participation next week.

Elsewhere, there is the threat of captain Steven Gerrard also missing the rest of the season.

The England midfielder was due to return from a groin operation against West Brom only to sustain a similar but not identical injury in training last week and a prognosis is not expected until Friday.

"Glen Johnson has a hamstring problem which is usually about three or four weeks and it's the same for Martin Kelly," said Dalglish of his current injuries.

"We will know about Steven at the end of the week. He will be assessed and we'll see what the story is.

"It's disappointing for the players because they want to play in every game.

"We're getting towards the end of the season but if you're injured you're injured.

"We feel for them but the most important people at the football club are the ones who are fit and able to play. We have to get on with what we've got."

The injuries only serve to make the club's quest to catch fifth-placed Tottenham and secure European football more difficult.

However, forward Dirk Kuyt has challenged the squad to go unbeaten until the end of the season, starting against City.

"For us it's a must-win game," said the Holland international.

"We have to move on from West Brom and there's another big game coming up. We have to make sure the three points stay at Anfield.

"Every game between now and the end of the season is a must-win for us and that's what we must try to do.

"We have to make sure we keep going and hopefully we can start a run by Monday.

"I think since the arrival of Kenny Dalglish we've had a pretty good run, but also some very disappointing results against West Brom and West Ham."

Liverpool, meanwhile, have dismissed reports they have agreed a pre-contract deal with Rennes winger Sylvain Marveaux.

The Frenchman will not play again this season because of a groin injury.