Lazio are set to be without Stefan de Vrij for the rest of the season after the Dutch defender underwent knee surgery on Wednesday.
Dutch international De Vrij is considered Lazio’s strongest central defender but he will be sidelined for six months as he recovers from the operation on his left knee.
A statement by the Serie A club said: “The surgery, performed by the Head of the Department of orthopedics and sport traumatology, Dr. Lagae, was a complete success and the expected recovery time for the resumption of competition is about six months.”
Lazio face Rosenborg in the Europa League on Thursday and, having beaten the Norwegians 3-1 in Rome earlier in the competition, are set to leave a number of key regulars at home.
They then face city rivals Roma at their shared ground of the Stadio Olimpico on Sunday and coach Stefano Pioli will rest Brazilian Felipe Anderson and striker Miroslav Klose for the trip to Norway.
Lazio sit top of Europa League Group G with a three-point lead over Saint Etienne.