Anfield hero may also miss the World Cup.
Liverpool striker Fernando Torres will miss the rest of the season following knee surgery.
The 26-year-old, who saw a specialist in Spain on Sunday, has been troubled by the problem for a number of weeks.
A Liverpool spokesman said: “It was decided that he would need surgery on a torn cartilage in his right knee.
“This will be carried out later on Sunday and, as a guide, the usual rehabilitation period for this type of procedure is around six weeks.”
His fitness will be closely monitored by Spain manager Vicente del Bosque, whose side’s opening World Cup game in South Africa is against Switzerland on 16 June.
Del Bosque must submit his final 23-man squad to Fifa by 1 June.
Torres, who joined Liverpool from Atletico Madrid in 2007, will also miss out on meeting his former club in the Europa League semi-finals.
The Spaniard has scored 22 goals in all competitions this season, despite being beset by various injuries.
He was sidelined for a month after a knee operation in January and before Christmas struggled with a groin injury. (BBC Sport)
This is not good news for Rafa. Our hopes of Champions League football are pretty much extinguished and without El Nino we could struggle to succeed in the Europa League and to be honest our chances of hitting the back of the net are going to take one hell of a hit.
We could opt to play Dirk Kuyt in his traditional role up front or give David Ngog a rare start although perhaps we could take this opportunity to give Daniel Pacheco the chance to impress. Maybe it would be a good idea to get Krisztián Németh back from AEK Athens?
We all know that we lack strength in depth up front and that is something Rafa should’ve dealt with before the season began and hopefully this summer he can find the cash to bring in some good back up goal scorers.