Assuming they're in, any matchup is going to be difficult. I love this team and how they've gutted out great wins, but there are fundamental flaws on offense that will make it very difficult to beat Alabama or Clemson.
Luckily Watson has been turnover prone this year, so I could definitely see the defense generating some short fields or points. They're going to have to figure out how to move the ball for more than one quarter though, and that probably means restricting the passing game quite a bit while getting creative in the run game. IMO, attempting 25-30 passes will get Barrett killed, so it's going to come down to the OL winning the LOS and figuring out ways to get the extra defenders out of the box or moving in the wrong direction.