Liverpool manager Kenny Dalglish fears that Martin Kelly will be ruled out of the meeting with fierce rivals Manchester United due to a hamstring injury.
The defender was forced off in the first half of Sunday's 3-1 defeat to West Ham after pulling muscle fibres when sprinting with the ball up a touchline at Upton Park.
Kelly was immediately substituted and, although Dalglish wants to wait for further analysis, the Liverpool boss thinks the 20-year-old will miss next Sunday's clash against United at Anfield.
Raul Meireles' afternoon against West Ham was also ended prematurely in the second half by a knee problem, but the full extent of the Portuguese playmaker's injury is not yet known.
Dalglish said regarding Kelly: "He has pulled his hamstring and Raul got a kick in the knee. Obviously Martin is more serious than Raul.
"With a hamstring he might be struggling for next Sunday, though I wouldn't take it as a given because I wouldn't know.
"But I would have thought with a hamstring it takes a bit longer than a week. With Raul we don't know."
It has been reported that Andy Carroll could make his debut against United, having been sidelined with a thigh injury since his £35million January arrival from Newcastle.
Dalglish said regarding the England striker: "He's better than bang on schedule.
"We never pencilled in a date when Andy's going to play. As soon as he's okay we'll get him involved.
"Whether that's next week, the week after or after that, we'll just have to wait and see.
"There is nothing that has happened since he came in that's had an adverse effect on his progress."