Johnson (left) and Agger (right) were both substituted in the first half of Saturday's defeat at West Brom

Liverpool have been hit by a double injury blow to defenders Daniel Agger and Glen Johnson.

Agger limped off in the first half of Saturday's 2-1 loss to West Brom with a knee injury that has ruled him out for the rest of the season.

Johnson will be sidelined for at least a month with a hamstring injury, also picked up in the first half of the defeat at The Hawthorns.

Fellow defender Fabio Aurelio is back in training after a hamstring injury.

It is a timely return by the Brazilian left-back, who has been sidelined for a month.

Liverpool boss Kenny Dalglish has also been boosted by the return of midfielder Jonjo Shelvey, who is back in training after making a successful recovery from a knee operation in February.

However, the loss of Agger and Johnson will leave the Reds short of numbers in defence for much of the rest of the season.

The tendon injury suffered by Agger, 26, is the latest in a string of injuries that has blighted the Denmark international's last two seasons.

quote 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.

And 26-year-old Johnson's absence will be keenly felt, with fellow right-back Martin Kelly expected to be out for four weeks after suffering a recurrence of his hamstring injury.

Both full-backs are likely to miss Liverpool's next four league fixtures - the home match with Manchester City on Monday, the trip to Arsenal six days later and the home games against Birmingham and Newcastle, on the 23 April and 1 May respectively.

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

Dalglish is still waiting for a prognosis on captain Steven Gerrard, who was due to return from a groin operation against West Brom only to sustain a similar but not identical injury in training on Friday.

The fact there has been no swift assessment of the problem raises fears the England midfielder's season could also be over.

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