ORCHARD PARK, N.Y. — If the new-look Buffalo Bills intend to shed their losing reputation, Mario Williams figures beating the defending Super Bowl champion Baltimore Ravens would be a good place to start.

"Having this coaching staff and all the new faces, that's our mentality," the defensive end said, with the Ravens hitting town Sunday. "In order for us to make that valid. We have to go out and win."

It might be easier said than done for the Bills (1-2), who haven't enjoyed a winning season since 2004, and have gone 13 seasons without a playoff berth.

Four weeks in, they're showing tell-tale signs of inconsistency following a tumultuous offseason in which they went through a top-to-bottom overhaul, including the hiring of new coach Doug Marrone. At least they've been competitive. All of Buffalo's first three games were decided in the fourth quarter, including two in the final 5 seconds.

The Ravens (2-1) went through their share of changes this offseason, particularly on a defense that lost veteran standouts Ray Lewis and Ed Reed. And yet, they have numerous key pieces in place on both sides of the ball to once again contend.

Bouncing back from a season-opening 49-27 loss at Denver, the Ravens have not allowed a touchdown over the past eight quarters. And their Joe Flacco-led offense has so far managed to overcome injuries to running back Ray Rice (hip) and receiver Jacoby Jones (knee).

That didn't prevent Lewis from publicly questioning the Ravens' leadership after Jones was hurt in an altercation while celebrating offensive lineman Bryant McKinnie's birthday this week.

"We've got a lot of leaders on this team," linebacker Terrell Suggs said. "We've got the Buffalo Bills. We can't be worrying about a comment that was made."

Here's five things to look for in Ravens-Bills:

DEPLETED DBs: Flacco has yet to build chemistry with his revamped group of receivers. He'll get an opportunity to develop that in facing Buffalo's injury-thinned defensive backfield.

Buffalo's already down starting cornerback Stephon Gilmore (broken left hand) and backup CB Ron Brooks (broken right foot). Add to that, starting cornerback Leodis McKelvin's hampered by a pulled right hamstring, while starting safety Jairus Byrd has yet to play because plantar fasciitis in both feet.

Bills third-year cornerback Justin Rogers was burned twice for 50-plus-yard touchdown passes against the Jets.

"I expect it," Rogers said of being tested early by Flacco. "I'm moving on and accepting the challenge."

SACK ATTACK: Led by Suggs' three sacks, the Ravens already have 11 on the season. And they're facing a rookie quarterback in EJ Manuel who looked lost handling the pressure in being sacked eight times in a 27-20 loss to the Jets.

The Bills don't need to guess what the Ravens' defensive approach might be this weekend.

"If I'm a defensive coordinator, that would be my biggest thing, too: stop our run and pretty much make our rookie quarterback beat them," running back C.J. Spiller said.

WAIT-A-MINUTE RICE: The Ravens running back has been a slow starter this season, missing last week's game against Houston. The Ravens abandoned their ground game early against the Broncos. Rice was limited to 13 carries after hurting his hip against Cleveland.

Rice was limited in returning to practice this week, but faces a promising matchup if he plays Sunday. The Bills have allowed at least 120 yards rushing in each game, including 182 against the Jets.

BILLS IN NEUTRAL: Buffalo's running game has yet to take much pressure off Manuel. Take away Spiller's 46-yard gain in a 24-23 win over Carolina, and Fred Jackson's 59-yard run against the Jets, and the Bills are averaging 3.3 yards per carry.

They face a defense that has yielded just two runs beyond 10 yards, and no touchdowns rushing.

THREE-AND-OUT: The Bills' hurry-up offense has so far been fast — in getting off the field.

Buffalo has converted just 14 of 45 third-down chances and is 0-for-2 on fourth down. It's a reason the team ranks 31st in the NFL, behind only Philadelphia, in time of possession (24:48).