Detroit Lions v New Orleans Saints
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New Orleans Saints quarterback Derek Carr left in the fourth quarter of their 33-28 loss to the Detroit Lions after being hit hard by Bruce Irvin in the backfield. Carr was slow to get up and eventually helped off the field by trainers, who were holding the veteran's right arm. Jameis Winston replaced Carr under center. 

Carr, who was officially listed as doubtful to return with shoulder and back injuries, also got evaluated for a concussion. The cart came out for Carr, but he eventually got up and walked off. Irvin was penalized for roughing the passer on the play in question. Check out what happened, here:

Carr completed 17 of 22 passes for 226 yards, one touchdown and one interception before leaving the game. Winston completed 2 of 5 passes for 41 yards in his place. 

Saints head coach Dennis Allen told reporters Monday that Carr is officially in the concussion protocol, and also being treated for a rib injury. 

This is actually the second time this season Carr has entered the concussion protocol. Allen was asked if he was concerned about that. 

"Any time you have a concussion, it's concerning," Allen said. "There is concern with some of the injuries (Carr) has suffered. Just like we do all the time, we'll go in and evaluate where he's at physically. Then, we will go from there."

Carr's status for New Orleans' Week 14 matchup against the Carolina Panthers appears to be in jeopardy. He will need to clear the league's concussion protocol before Sunday's 1 p.m. ET game.