AC Milan have announced that defender Alessio Romagnoli has sustained a thigh injury.
The 22-year-old has damaged a muscle and is therefore a major doubt for Monday's key Serie A clash with Lazio at the Stadio Olimpico.
"AC Milan announces that Alessio Romagnoli today underwent a medical examination that revealed an injury to his right thigh flexor," a Milan statement confirmed.
The news is a major blow to head coach Vincenzo Montella, who has been forced to field a makeshift defence in Milan's last two matches.
Romagnoli was used at left-back for the 1-0 defeat to Sampdoria at San Siro on February 5, with Cristian Zapata and Gabriel Paletta partnered in the middle and Juraj Kucka deployed as an emergency right-back.
Paletta was sent off during the 1-0 win over Bologna this week, leaving Montella desperately short of options now that Romagnoli is expected to be sidelined.
Gustavo Gomez is expected to deputise at the heart of the defence, while Primavera youngsters Raul Zucchetti and Matteo Gabbia are reportedly set to be called up to the main squad.
A win would see Milan move level on 43 points with fourth-place Lazio and keep alive their faint hopes of challenging for a Champions League spot.