Liverpool will work feverishly during the international break to find a solution to Daniel Agger's on-going back problem.
The Denmark international played in last week's Champions League 1-1 draw in Lyon, and also in Monday's stalemate with Birmingham.
But boss Rafa Benitez revealed his concerns about the player's injury problem that has dogged him all season and needed an operation during the summer.
After the 2-2 draw with Birmingham, Benitez talked of the persistent problems facing Fernando Torres and new hamstring injuries for Albert Riera and Yossi Benayoun, but it was the worrying performance of Agger that seemed to concern him most.
He said: 'Daniel has more problems with his back, it is a concern for us.'
So much so that Agger has withdrawn from Denmark's friendlies during the international break against South Korea and the USA - his country having already qualified for the World Cup finals.
Benitez's concerns for Agger are explained because he is desperately needed for the next two Barclays Premier League matches against Manchester City and Everton.
Fellow defender Jamie Carragher will be completing his three-match suspension and misses both of those key matches.
If Agger is not fit, Benitez has only a fledgling partnership of Martin Skrtel and Sotirios Kyrgiakos in central defence for those two vital games.
The pairing looked anything but secure in their one game together, the Carling Cup defeat at Arsenal.
Benitez said: 'We thought that Agger would be OK to play against Birmingham, but you could see he was not right, his back was giving him problems again.'
Liverpool will spend the international break nursing Torres and Steven Gerrard back to fitness as they struggle with groin problems.
Benitez would not speculate on whether Torres will be fit to face Manchester City on November 21, suggesting: 'He is having treatment that could keep him out for two or three weeks. Gerrard seems OK, we will be careful with him.'
Both players were omitted from the Spain and England national squads, respectively, for weekend internationals.
Glen Johnson will also look to recover fitness after he pulled out of England's squad to face Brazil.
Positive: Aquilani is finally getting games under his belt
That will aid Benitez's cause with summer signing Alberto Aquilani finally looking set for an extended run in the side after making his Anfield debut as a second-half substitute against the Blues.
Benitez said: 'The plus points are that Johnson was back and playing well, while Aquilani finally got a chance to play at Anfield.
'It was a difficult time for him to come on, with us battling for the third goal against a packed defence.
'There were negatives with new injuries, but the positives are that we had two players making an impact.'
Javier Mascherano has been called up for Argentina's friendly with Spain on Saturday, but there is no place in Diego Maradona's squad for Emiliano Insua.
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