GREEN BAY, WIS. (AP) -- For a team that came into the season with Super Bowl expectations, it didn't take very long for the Green Bay Packers to hit their first serious speed bump.

Running back Ryan Grant is out for the year with an ankle injury, and backup Brandon Jackson is stepping in as the starter. Jackson's main backup, at least for now, is ... a fullback?

Still, Buffalo Bills coach Chan Gailey didn't focus on Green Bay's running back shortage going into Sunday's game at Lambeau Field. The Packers remain a pass-first team, and the name of quarterback Aaron Rodgers might have come up a time or two - or 20 - in Bills team meetings this week.

"About every other sentence, every other word was 'Aaron Rodgers,"' Bills safety George Wilson said. "We know he's the pulse of their team, the pulse of their offense. And we have to do a great job of keeping them off balance, not really allowing him to get in a groove."

Coming off an impressive 2009 and a sharp preseason, Rodgers wasn't happy with his play in the Packers' Week 1 victory at Philadelphia. He threw for 188 yards with two touchdowns and an uncharacteristic two interceptions, misfiring on several other throws.

"We're 1-0, and we're excited about that, but offensively we just want to take some of the burden off the defense," Rodgers said. "If we can hold the ball longer and not put our defense in the compromising situations with the turnovers we had, then I think we're going to be able to play a more complete game."

Rodgers knows he'll face a talented and deep secondary Sunday. The Bills finished second in the league last year with 28 interceptions, trailing only the Packers' 30.

"Our defense doesn't lack confidence," safety Jairus Byrd said. "I know that there's areas that we need in to improve in, but we're up to the challenge and excited about it."

But much like the Packers were at this point last season, the Bills are in the middle of a transition to a 3-4 defense. And Buffalo has injuries of its own; linebacker Paul Posluszny will miss a few weeks after spraining his right knee last weekend and the Bills already lost veteran backup Kawika Mitchell to a season-ending foot injury. Linebacker Reggie Torbor is expected to be ready after missing last week's game with a chest injury.

Gailey knows Rodgers and the Packers will challenge his defense.

"They're always putting a little bit of doubt in your mind," Gailey said. "If you put a little bit of doubt in somebody's mind, you gain an advantage. They've been able to work every situation the way they want to work it. He knows where to throw the football, he can read defenses and he's been in this offense for quite a while now. We just see a guy that's very comfortable."

But the Packers had pass protection problems against the Eagles early Sunday - an ugly flashback to last season, when they gave up a league-worst 51 sacks. The Packers' line rebounded to keep Rodgers relatively clean the rest of the game, but only after they established the run.

That will be more challenging without Grant.

Jackson, a second-round pick out of Nebraska in 2007, has been emerging as a productive third-down back. But Grant has set a high standard, staying healthy and surpassing the 1,200-yard rushing mark in each of the past two seasons.

Even more disconcerting is the Packers' lack of depth.

Behind Jackson is fullback John Kuhn, who has shown enough ability with the ball in his hands to be considered an insurance policy at halfback. The Packers signed running back Dimitri Nance off the Atlanta Falcons' practice squad this week, but it's not clear how much he'll be able to contribute after only a few days with the team.

Tight end Jermichael Finley says Grant's injury won't stop the Packers.

"If we want to be a Super Bowl team, we can't let it deflate us or roll on top of us," Finley said. "We've got to keep trucking, and keep that swagger going."

And the Packers might not need a whole lot of points to beat the Bills, if Buffalo's performance against Miami last week is any indication. The Bills are hoping for an offensive resurgence under Gailey, but it hasn't come yet.

After showing some spark in the preseason, the Bills' 166 yards of total offense against Miami were the fewest of any team to open the season last week.

Running back C.J. Spiller, the Bills' highly regarded first-round pick, was held to six yards on seven carries and knows it will take some time to adjust to the NFL game.

"Of course it's tough," Spiller said. "For a fast guy, it's going to be tough because they're ready to get going, but that just comes through the learning process. Through more games and getting a better feel for how things are, I'll do a better job at it. It won't take me long to get adjusted to that part."

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