The morning session went for more than two hours and finished with goal line and 7-on-7 red zone.

Gilmore rounding into form

In a return from offseason hip surgery Stephon Gilmore has been making a slow but steady climb back to where his game was at near the end of last season. Gilmore has been putting in work with more first team reps the past week and a half, and on Wednesday signs of the aggressive, ball hawking cornerback were evident.

Gilmore had three pass breakups in practice Wednesday, more than any other defender and appreciated being tested. He knows being challenged in the passing game will get him back to full form faster.

"I'm working towards it," Gilmore told Buffalobills.com. "I've still got a lot to do to get where I want to be. It's one thing to get to where I was last year or my rookie year, but I want to be way better than that, so I'm just trying to put the work in to be that guy. I'm trying to do whatever it takes to be good."

On his second pass breakup of practice the third-year cornerback forcefully swatted away a pass intended for Marcus Easley. His last PBU came in 7-on-7 red zone when he knocked away a fade pass attempt to Mike Williams from EJ Manuel.

After practice Gilmore was doing extra man coverage work. He then went over to the JUGS machine to work on tracking passes for interceptions. All told it was an extra 20-30 minutes put in by the former first-round pick.

As much as Gilmore has worked on getting the physical part of his game all the way back to where it was, he understands his mental acuity has to be there on every snap as well.

"You've really got to be focused on the island," he said. "There are no mistakes. One mistake and there's a big play, so you've really got to be focused every play. If you're not focused on one play it can be bad. I'm just trying to focus and get better and work on my craft and make plays for the team."

Gilmore is encouraged by his progress, but maintains that live reps in this Saturday's preseason game will be a more accurate gauge for him as to where his game is at just two weeks before the regular season opener.

"In practice you have a couple of good days, but until you step on the game field that's when you know," he said. "In practice you play a certain technique and in the game you've got to really slow it down. It's different. Once you play in the game you can figure it out. That's why you've got to play in a game and get reps. That's why I'm out here working on what I didn't do right in the game to make myself better."

McKelvin leaves with groin injury

Leodis McKelvin was making good progress. On Monday and Tuesday he was a full scale participant in practice and fully planned to play in Saturday's preseason game. Now those plans could be in jeopardy after he left practice Wednesday with a groin injury.

At the close of practice head coach Doug Marrone did not yet know the severity of McKelvin's latest setback.

"I have no idea," he said. "They haven't told me that yet."

Knowing this is the most critical preseason game for starters and the fact that McKelvin has yet to play in the preseason coming off of offseason hip surgery, not being able to play Saturday against Tampa Bay would be unfortunate for the six-year veteran.

Marrone used to have a rule in place that players had to practice leading up to a game, but he's amended that.

"I think at this level every player is different. Someone with more experience who has done it, sometimes you don't get worried (about them playing)," said Marrone. "Sometimes if it's a young player and you put him in there and he makes a mistake, it's almost like a built in excuse. You know what I mean? Well he didn't practice. What do you expect? Well, then that's on us as coaches."

In an ideal world McKelvin gets game reps on Saturday to help him get re-acclimated to game speed, but the primary goal is to be healthy for the start of the regular season. Depending on the severity of the injury that could rule out any chance of him playing this weekend.

Run game looks healthy

The last two days of practice the lanes for the run game have appeared to be wide open. Perhaps it's due in part to the offensive coaches trying to fit run game calls to the scout team looks of Tampa Bay. Still in all there were sizable holes for Buffalo's backs to run through.

C.J. Spiller had three productive runs early and Fred Jackson had a pair of runs that went for first down yardage as well. Jackson's second big run came on a good decision when a cutback lane widened for him. Coming off a respectable outing against the Pittsburgh run front the Bills believe they can have a lot of success on the ground this season.

"I think we have a great stable of running backs and if we can put a hat on a hat they're going to make us look really good this year," said Eric Wood.

Offensive coordinator Nathaniel Hackett has also been getting positive feedback from the backs themselves about the design of the rushing attack as well.

"I think we've tried to add a lot of different things to change some things up but still kind of continue the foundation of what we started last year, push forward with that and make it so the guys are comfortable with it," Hackett said. "The corrections can be made easily. They really like the run game. We have some nice code words about it that they've made up because they love to run the ball so much. Those running backs are good and we have a lot of them."

Top O-line settling in

Buffalo's top O-line unit went into its third day of their new combination with the right side of the line consisting of Seantrel Henderson at right tackle and Erik Pears moving inside to guard. The transition has been relatively smooth when it's come to execution.

"At this point, we want to get the best five on the field, that's always the biggest thing for us," said offensive coordinator Nathaniel Hackett. "We always want to have the best players out there, and we want to make sure we've got the right guys. Getting Cordy Glenn back was obviously a huge benefit, but we've seen a lot of good play from some other guys. We want to be sure we've got the best combination put together and move forward."

Pears, who has not played guard in more than four seasons, earned some praise from his head coach based on his play the past three days.

"Erik is probably one of the best pros that I've been around and I've been around some good ones, guys that have played a long time," Marrone said. "I talked to him about, 'Hey, we're going to put you inside and see how that works.' No problem. When people talk about someone being a true pro and doing whatever you can to help that football team, he's done that 110 percent. He's looked good in there."