Lazio will be without Stefano Mauri for at least a month, Sky Sport Italia are reporting on Friday.
The attacking midfielder picked up a problem in training this week which will require a lengthy spell on the sidelines.
According to reports, the Italian international has pulled a muscle in his thigh which will see him out for between 30 and 40 days.
"Unfortunately, I hurt myself," Mauri said on Thursday. "During yesterday's session I felt it 'pull' and had to stop.
"I really could've done without this, as I was fired up and felt great."