Here are the five players to keep an eye on in Buffalo's preseason opener.
Matt CasselThe veteran quarterback probably won't see a ton of action, perhaps just the first quarter, but how he performs will be under close scrutiny. Cassel has received the majority of the reps in training camp with the first unit and needs to demonstrate that his chemistry with some of the team's top passing targets is making progress.
Ronald DarbyDarby has had a solid first two weeks of training camp after being thrust into the starting lineup due to the ankle setback suffered by Leodis McKelvin. While there is no questioning Darby's quickness and catch up speed, what will bear watching is how he fares against a much bigger receiver like his former Florida State teammate Kelvin Benjamin.
Marqueis GrayThe tight end has very quietly had a consistent camp. Based on reps in camp he's served as the backup to Charles Clay and most closely represents his versatile skill set among the other tight ends on the roster. He'll see far more playing time than Clay and must show a firm grasp of all the assignments entrusted to that position in Greg Roman's scheme.
John MillerThe rookie right guard has done nothing to disappoint since being plugged into the starting role in the spring. He's likely to play a bit longer than some of the other starters to get some additional game experience. How he fares against an interior defensive front with the likes of Kawann Short and Star Lotulelei will be interesting to see.
Cedric ReedThe undrafted rookie defensive end from Texas has been getting a lot of quality reps in training camp playing in Mario Williams role with the second unit. He'll need to prove all of those snaps in practice can lead to production in Friday's game knowing Reed will be getting a good deal of playing time.