W2W4: Bills' first practice

PITTSFORD, N.Y. -- The Buffalo Bills will hold their first practice of training camp on Sunday evening (6-9 p.m. ET), becoming the final NFL team to officially kick off their preparations for the regular season.

For the 14th consecutive year, the Bills are training at St. John Fisher College in Pittsford, N.Y. Here's a look at what to look for Sunday:

1. Quarterback battle takes center stage. With such a late start to their training camp -- a result of not playing their first preseason game until Aug. 11 -- the Bills will have a tight window in which to evaluate rookie quarterback EJ Manuel. It would be a surprise if the Bills wait until late August to name an opening day starter at quarterback, meaning the clock on Manuel will be ticking beginning Sunday night. Head coach Doug Marrone said Manuel and veteran Kevin Kolb will split reps at quarterback to begin camp, but if Manuel struggles in his first week of practice, the pendulum could quickly swing to Kolb. With a new offensive system and several young receivers to develop, the Bills can't afford not to pair their most consistent quarterback with their top pass-catchers in practice.

2. Where do pieces fit under Pettine? The Bills have seen several scheme changes on defense in recent years, and first-year defensive coordinator Mike Pettine will bring yet another system to town. Pettine coached a New York Jets defense that played in back-to-back AFC Championship Games just three seasons ago, and he will have pieces to play with in Buffalo. The biggest question mark, though, might be defensive lineman Marcell Dareus. The Bills hope that Pettine can get more out of the third overall pick in 2011, but others in camp -- notably Alex Carrington, who is in the final year of his rookie contract -- might push him for playing time. If Dareus isn't lining up with the top defensive unit Sunday evening, it will be an indication of how much Pettine and his staff see Dareus contributing this season.

3. Who's the left guard? The Bills are still looking to fill the void left by Andy Levitre, who departed via free agency this offseason. There are several players vying for the starting left guard spot, and Sunday evening will give a glimpse into where things stand in that battle. Will Colin Brown return from a season-ending injury and take first-team reps? Will newcomer Doug Legursky, who has significant NFL experience with the Pittsburgh Steelers, push for the job? Or will the Bills mix and match and give multiple players snaps with the top unit? It will be something to keep an eye on.

4. What's the vibe from Marrone? Every NFL head coach has his own unique style, and Sunday will be the first chance for the public to see how Marrone runs his practices. Everything from the pace of practice, use of music, and level of contact (although the Bills won't be in pads on Sunday evening) are tools coaches use to develop the culture of their team. Coaches making the jump from college to the NFL in recent years -- Pete Carroll, Greg Schiano, and now Marrone and Chip Kelly -- all have faced challenges adjusting to coaching NFL players.

WEATHER REPORT: There was morning rain and it remains cloudy in the Pittsford area, but it is expected to stay dry for tonight's practice under the lights at Growney Stadium.