Atletico Madrid president Enrique Cerezo expects Tiago to be out for at least three months after suffering a broken leg in Saturday's 1-0 victory over Espanyol.
The midfielder collided with Marcos Asensio in the 33rd minute of the game, with a subsequent scan revealing the extent of his injury.
Cerezo was joined by a group of players in visiting the Portuguese veteran at hospital while he awaited surgery the following day.
However, the president is optimisitic Tiago, who has been outstanding for Diego Simeone's men, can return before the end of the season.
"In spite of the injury he's fine and keeping his spirits up. I think he'll be out for three months," Cerezo told reporters.