The Brazilian stopper suffered the setback in training prior to the Old Lady's 2-0 win over Parma on Saturday, and may now face a prolonged period on the treatment table
The defender, 34, pulled up in training on Friday, prior to his side's 2-0 opening-day success over Parma in Serie A on Saturday, with what initially appeared to be a sprain.
However, after further scans, the club announced that the Brazilian defender suffered a "complete lesion" of his anterior talofibular ligament and is likely to face an extended spell on the sidelines.
"Lucio had to stop training yesterday with a sprained right ankle. This morning, he was examined," a statement read.
"The nuclear magnetic resonance and X-ray showed a complete lesion of the anterior talofibular ligament."
Midfielder Luca Marrone filled in for the former Inter and Bayern Munich man at centre-back against the Gialloblu, as the Old Lady kicked off the defence of their Scudetto shield.