Reigning Super Bowl MVP Patrick Mahomes left Sunday’s game in the third quarter after suffering a concussion on a running play in the Chiefs 22-17 win over the Cleveland Browns. After being helped off the field, Mahomes went directly into the training tent and then ran up the tunnel to a training room for more tests. Moment later, Mahomes was ruled out for the remainder of the game.

Following the game in his post-game press conference Andy Reid said that Mahomes was “doing great right now, passed all the deals that he needed to pass.”

That does not guarantee Mahomes return for Sunday’s AFC Championship game. The NFL has a five-phase approach to a player returning to game action.

PHASE 1: The player is prescribed rest until the signs and symptoms and neurological examination, including cognitive and balance tests, return to baseline status.

PHASE 2: Under direct oversight of the team’s medical staff, the player should begin graduated cardiovascular exercise and may also engage in dynamic stretching and balance training.

PHASE 3: The player continues with graduated cardiovascular exercises that are increased and may mimic sport-specific activities, and supervised strength training is introduced.

PHASE 4: The player continues cardiovascular, strength and balance training and participates in non-contact football activities (e.g. throwing, catching, running, and other position-specific activities.

PHASE 5: Upon clearance by the team physician for full football activity involving contact, the player must be examined by the Independent Neurological Consultant (INC) assigned to his club. If the INC concurs with the team physician that the player’s concussion has resolved, he may participate in the club’s next practice or game.

The Chiefs host the Buffalo Bills Sunday at 5:40 CT.