Midfielder was forced off during the 1-1 draw with Gillingham.
Bradford City have confirmed that Filipe Morais suffered shoulder ligament damage during Saturday's fixture with Gillingham.
The in-form performer was forced off only 18 minutes into the contest after failing awkwardly early into the match.
X-rays after the game showed no bones were broken though.
The club say they'll have to wait for the swelling to go down before they know when he might be able to return.
Manager Phil Parkinson said: "The checks have revealed that nothing is broken but he has damaged ligaments in his shoulder. It is a set back for Fil, especially the way he has been playing lately.
"We'll wait for the swelling to go down before getting a better idea of how long he'll miss.
"We picked up a few other knocks during the (Gillingham) game - nothing major - but we'll monitor those as well."