Liverpool have injury worries up front ahead of Saturday's match at home to Wigan after both Fernando Torres and Ryan Babel limped off while on international duty.
Torres, the Barclays Premier League joint top scorer with five goals, lasted less than 16 minutes of Spain's World Cup qualifier against Belgium on Wednesday night after reportedly feeling a tweak in the muscle in the back of his left leg.
Spain team doctor Oscar Celada told Spanish television: "He has intense pain in the back part of the thigh. It is difficult to diagnose now exactly the extent, if it is a question of a strain or a small tear. If it is a strain then he could be out for about a week."
Torres has struggled with hamstring problems before, most recently at the beginning of September when he was sidelined for the international break after tearing the muscle in the goalless draw against Aston Villa.
If he is ruled out for a week Torres would not only miss the match against Wigan but also the Champions League clash against former club Atletico on Tuesday and could potentially be a doubt for the trip to Chelsea the following Sunday.
Babel was also forced off in Holland's 1-0 victory in Norway.
The 21-year-old, who has operated predominantly on the left wing for Rafael Benitez's team but who can play as a centre forward, was substituted after 26 minutes but the nature of his injury has not been disclosed.
Meanwhile, the venue for Liverpool's Champions League clash in Spain is still to be finalised. Atletico are awaiting confirmation the stadium ban imposed by UEFA has been postponed.
On Tuesday European football's governing body ruled the club must play their next two Champions League matches at least 200 miles from the capital - a third game was suspended - while they were also fined £117,000.
Reports in Spain, however, indicated UEFA have had a change of heart and will instead allow the match to be staged at the Vicente Calderon. Atletico have received the full backing of the Spanish government.
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