Lucio is effectively out of Inter's trip to Bayern Munich and could be sidelined for some time after suffering an upper thigh strain.
The defender limped off during last night's 1-1 draw with Brescia at the Stadio Rigamonti.
“Tests today confirmed a strain to the gluteal muscles in his right leg,” read a club statement.
“The player has already undergone his first physiotherapy sessions.”
It means Lucio misses the visit back to his former club in the Champions League on Tuesday evening.
However, it's unclear how long the Brazilian will be out for, as there could be several weeks on the sidelines.
Esteban Cambiasso and Cristian Chivu took part in full training today, having missed the Brescia game.
Thiago Motta and Diego Milito are still on a personalised fitness schedule along with long-term absentee Walter Samuel.