The Kansas City Chiefs' hopes of getting superstar quarterback Patrick Mahomes back for the conference championship game against the Buffalo Bills on Sunday just suffered a significant setback. After being placed in the league's concussion protocol, Mahomes was reportedly unable to answer all the test questions correctly.

According to an unnamed source, Mahomes incorrectly answered one game-related question (h/t Carrington Harrison):

“Following the hit, Mahomes was asked a series of questions as part of the NFL's concussion protocol. Mahomes answered all of the questions correctly but 1 specific game related question. W/ failed question + physical symptoms, he was not cleared to return”

Mahomes suffered the brain injury during the Chiefs' Divisional Round win over the Cleveland Browns. The reigning SuperBowl MVP was forced to exit the game after a brutal hit by Browns linebacker Mack Wilson. Mahomes was unable to return to the game, and it was later revealed that he had suffered a concussion. The NFL placed Mahomes in the league's concussion protocol, which meant that there was some real danger of the QB missing K.C.'s matchup against the Bills.

Unfortunately for Mahomes and the Chiefs, their star quarterback was reportedly unable to pass the league's concussion protocol test, which means that he has yet to receive clearance for Sunday's highly-anticipated game.

It remains unclear if and when Mahomes will undergo another test, but at this point, it is looking likely that the Chiefs will be without him when they battle out a spot for SuperBowl LV against the Bills on Sunday.