Liverpool pair Yossi Benayoun and Albert Riera could be out for at least three weeks with hamstring injuries.
Both players limped out of Monday's Premier League draw against Birmingham, adding to manager Rafael Benitez's injury concerns.
Daniel Agger and Glen Johnson also suffered injuries in the same game while the club continue to monitor key duo Steven Gerrard and Fernando Torres.
Manager Rafael Benitez said of Benayoun and Riera: “We will have to wait and see how they progress but hopefully in three weeks they could be available.
“We are disappointed because there are too many things at the moment that we can't change.
“Both players are wingers as well and for them to be out at the same time is bad news for us.”