According to Ian Rapoport of NFL Network, McCarron underwent testing for a few days and discovered he didn't suffer a hairline fracture during the Bills' preseason win over the Cleveland Browns on Friday. Rather, he is day-to-day while waiting for the soreness to dissipate, although Rapoport said it "sounded like he was in a lot of pain so unclear when that is."
This comes after Vic Carucci of the Buffalo News reported McCarron suffered a hairline fracture in his collarbone during the first quarter against Cleveland.
Buffalo overhauled its quarterback depth chart this season, signing McCarron and drafting Josh Allen after trading Tyrod Taylor to the Browns.
McCarron sat behind Andy Dalton during most of the first four seasons of his career on the Cincinnati Bengals, although he threw for 854 yards, six touchdowns and two interceptions across seven games in 2015.
While the soreness will seemingly keep the Alabama product sidelined for an undetermined amount of time, he has a much better chance of seeing the field in the near future than he would have with a hairline fracture.
Still, the Bills announced Allen will start Sunday's preseason contest against the Cincinnati Bengals after the rookie impressed against Cleveland.
Buffalo selected Allen with the No. 7 overall pick in April's draft. He demonstrated the ability to hit targets underneath while also mixing in long throws with his strong arm when he went 9-of-13 for 60 yards and a score against Cleveland.
Nathan Peterman is also competing for Buffalo's starting gig, but the Bills didn't spend a top-10 pick on Allen to make him sit on the bench for years to come. Even with McCarron listed as only day-to-day, Allen has the chance to create separation between himself and the other candidates in the race to start with a promising showing against the Bengals.