Jan. 19 (UPI) -- The playing status of Kansas City Chiefs quarterback Patrick Mahomes is in question ahead of Sunday's AFC Championship game. Mahomes must first pass several tests to clear the NFL's concussion protocol.
Mahomes was forced out of the Chiefs' win over the Cleveland Browns in the AFC Divisional Round midway through the third quarter on Sunday in Kansas City, Mo. He took off on a run before he was taken down awkwardly by Browns linebacker Mack Wilson.
Chiefs players had to help Mahomes get to his feet before he went to the locker room. Chiefs coach Andy Reid said after the game that Mahomes was hit in the back of the head and it "knocked the wind out of him and everything else."
Reid also said Mahomes was "doing great" and passed the tests "he needed to pass" after the game. The Chiefs coach updated Mahomes' status on Monday.
"He's in the protocol," Reid told reporters. "We'll just follow that and see how he does here in the next couple days."
Players enter the NFL's game-day concussion protocol if they "exhibit or report symptoms or signs suggestive" of a concussion or a nerve-pinch injury. Team athletic trainers, the trainer's spotter, team doctors, NFL game officials, coaches, teammates or unaffiliated neurotrauma consultants also can initiate the protocol for a player.
Players diagnosed with a concussion must complete a five-step process before they are cleared to fully participate in practice or NFL games. The protocol states that there is "no set time frame for return to participation."
The first phase of the return-to-participation protocol involves what the NFL calls "symptom limited activity." The player in the protocol is prescribed rest and limited or no physical or cognitive activities that could increase or aggravate symptoms. They also are under supervision by their team's training staff.
The player then can resume stretching and balance training and progress to light aerobic exercise. The second phase of the protocol introduces more cardiovascular exercise, balance training and dynamic stretching. At that stage, neurocognitive and balance testing should be at a "baseline" level.
The third stage of the protocol also features supervised cardiovascular exercise and a reintroduction to strength training. At that stage, players are allowed to practice with their team in football-specific exercises for 30 minutes or less.
The fourth stage clears players for non-contact training drills like throwing, catching, running and other position-specific activities. Players also must have baseline results from balance and neurocognitive testing at that stage of the protocol.
The final stage of the protocol clears players for contact and full football activities.
After the player has completed the five-step process, and is cleared by his team doctor, he also must be seen and cleared by an independent neurological consultant. The consultant is approved by the NFL and players union and not affiliated with any NFL team.
Reid said he would just "leave it with the doctors" when asked about Mahomes' status for Sunday's game.
"Because of the protocol, you just have to go forward and make sure you have an answer if he's there [cleared] and if he's not there," Reid said.
Mahomes also sustained a toe injury on Sunday, but Reid said he thinks the All-Pro quarterback will be "OK" to play through that ailment.
Reid on Monday declined to say if he would allow Mahomes to play if he was cleared on Sunday morning, without prior practice sessions.
Chad Henne -- who played in relief of Mahomes in the win over the Browns -- is in line to start for the Chiefs if Mahomes is not cleared to play.
The Chiefs host the Buffalo Bills in the AFC Championship game at 6:40 p.m. EST on Sunday at Arrowhead Stadium in Kansas City.