Liverpool manager Jurgen Klopp has revealed that Lucas will be sidelined for six weeks with a unique quad injury.
The Brazilian, a central midfielder by trade, has deputised at centre-half amid an injury crisis at Anfield, with regular defenders Martin Skrtel, Mamadou Sakho, Dejan Lovren and Kolo Toure all suffering injuries at some stage.
Lucas excelled in the position against FC Augsburg in the Europa League, helping the Reds advance to the last 16, where they will face Manchester United.
Klopp then played the 29-year-old in the centre of defence from the start in the Capital One Cup final against Manchester City at Wembley.
Liverpool held Manuel Pellegrini’s side to a 1-1 draw after extra-time, but prevailed on a penalty shootout, with Lucas one of those who missed for the Reds.
Klopp revealed that Lucas injured himself taking the penalty, saying: “Lucas is really unfortunate, a little bit more serious [than first thought].
“I’ve never heard about an injury you can get like this.
“I don’t know exactly, but five or six weeks [out]. It’s not too good.”
Klopp added: “I have some hard selection decisions to make.
“We haven’t had this before. We have to use this new quality to change and rest.”
Sakho back training but only did a light session, Sturridge trained completely normally. #LFC
— James Pearce (@JamesPearceEcho) March 4, 2016