Buffalo Bills quarterback Josh Allen is listed as questionable for his team's Week 5 matchup with the Tennessee Titans on Sunday as a result of still being in concussion protocol, according to Josh Alper of Pro Football Talk.

Allen was a full participant in practice on Friday, but he still needs to be cleared in order to play this weekend.

The second-year signal-caller left the Bills' loss to the New England Patriots in the fourth quarter last Sunday after taking a vicious hit to the head from Patriots cornerback Jonathan Jones.

Allen had a nightmarish outing against the Patriots, completing just 13 of his 28 passes for 153 yards and three interceptions. On the season overall, he has thrown for 903 yards, three touchdowns and six picks while completing 60.3 percent of his throws and posting a passer rating of 69.6.

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The 23-year-old, who played his collegiate football at the University of Wyoming, was originally selected by Buffalo with the sixth overall pick of the 2018 NFL Draft.

He played in 12 games and made 11 starts during his rookie campaign, finishing with 2,074 yards, 10 touchdowns and 12 interceptions while completing just 52.8 percent of his passes and registering a passer rating of 67.9. He did, however, rush for 631 yards and eight scores.

The Bills jumped out to a 3-0 start this season but put forth an ugly offensive performance in a 16-10 loss to the Patriots in Week 4, dropping them to 3-1 and vaulting New England into sole possession of first place in the AFC East.

Buffalo has made just one playoff appearance since the 1999-00 campaign.