Lazio will have to do without goalkeeper Fernando Muslera for two to three weeks after he sprained his ankle.
The Uruguayan shot-stopper will be out of action for at least 10 days before undergoing another check-up, announced a club statement.
Muslera was warming up for Sunday's 1-0 win over Bari when he jumped to catch a ball and fell awkwardly on to his ankle.
“It's nothing too serious,” he assured. “They told me I'll be out for around 20 days, but I hope to make it back earlier than that. I'll definitely play in the derby.”
Lazio are set to face their local rivals Roma on March 13.