ORCHARD PARK, N.Y. -- The Buffalo Bills' secondary has been ravaged by injuries early this season, with their top two cornerbacks and top safety inactive for Sunday's game against the Baltimore Ravens.

Expectations for Buffalo weren't high: Ravens quarterback Joe Flacco, the defending Super Bowl MVP, was supposed to have a field day.

But apparently the Bills' cast of back-end replacements didn't get that memo. Flacco threw five interceptions, was sacked four times, and Baltimore's offense was 3-for-16 on third downs as the Bills defeated the Ravens, 23-20.

Leading the charge was Aaron Williams, who has been tossed around in the Bills' defense. Drafted as a cornerback in 2011, Williams struggled in his first two seasons and was converted to safety this offseason. But McKelvin's injury last week forced Williams back to cornerback, where he started Sunday.

Williams intercepted Flacco twice despite himself being hobbled by an early-game shoulder injury and, later, a lower back contusion. He did not finish the game and said he is unsure of his status for Thursday's game in Cleveland.

"Last year, I wasn't really aggressive about getting the ball," he said. "If you really want to be great, you need to go get that ball."

Williams was flagged for a horse-collar tackle that set up a Ravens touchdown in the third quarter, and also was beaten on a 74-yard completion in the fourth quarter. But the Bills have to be pleased with Williams' overall performance, switching positions in a pinch.

"I can't complain about two interceptions, but at the same time, I can't give up the big plays like that toward the end," Williams said.

Head coach Doug Marrone said the Bills would like to have Williams return to safety, but they also want him to settle in at one position instead of worrying about when McKelvin or Byrd may return.

"We made a commitment saying we're going to put him at corner and then we'll take care of the safety positions," Marrone said.

Safety Jim Leonhard, who has become a full-time player when Williams returned to cornerback, also had an interception, but was quick to praise Williams after the game.

"It's unbelievable," he said. "There are not many guys in this league that can go back from safety to corner and play the way he did and gut it out. He's nowhere near 100-percent right now, but to go out there and play the way he did, you have to give him a lot of credit. I think he's earned a lot of respect."