Juventus are set to be without Giorgio Chiellini for their top-of-the-table clash with Napoli and the first leg of their Champions League last-16 tie with Bayern Munich.
The Italy defender picked up a leg injury 13 minutes from time in Juve's 2-0 win over Frosinone on Sunday.
And in a huge blow for coach Massimiliano Allegri, Chiellini will miss Saturday's crucial visit of Napoli and Serie A and is a major doubt for Juve's first leg against Bayern on February 23.
In a training update on Tuesday, Juve confirmed: "Missing out on this morning's session was Giorgio Chiellini, who underwent a series of tests after departing the action towards the end of last weekend's clash at the Stadio Matusa.
"These revealed a torn soleus muscle in his right leg, an injury that is expected to keep him out for up to 20 days."
Chiellini could also face a race against time to be fit for Juve's Serie A meeting with Inter on February 28.
Allegri already looks set to be without the likes of Kwadwo Asamoah, Sami Khedira and Mario Mandzukic for the game against Napoli due to injury.
But full-back Patrice Evra should return from illness after missing the win over Frosinone.
