Cary Williams said that Sunday's 48-30 loss to the Vikings, in which journeyman quarterback Matt Cassel completed 74 percent of his passes and threw for 382 yards and two touchdowns, knocked the Eagles "off our high horse."

"We thought we [were] good or we thought we would be able to just go into Minnesota and win and those guys would lay down," Williams said Tuesday. "It definitely served as something that was kind of bittersweet at the time. I think it was sad we lost - the bitter part - but it was sweet that we lost at the end of the day because it helped humble us.

"We didn't want to go into this week thinking that we were invincible."

As quotable as Williams may sometimes be, it's difficult to believe that the Eagles went into Sunday night's game against the 8-6 Chicago Bears thinking they were invincible, even if they had beaten Minnesota to win six straight.

Although Bill Davis' bend-but-don't-break defense had held opponents to 21 or fewer points over the previous nine games, it was only a matter of time before his patchwork secondary unraveled. The surprise was that it was Cassel and an average group of receivers who did it.

With receivers Brandon Marshall and Alshon Jeffery and a good-but-not-great quarterback in Jay Cutler, the Bears have considerably more firepower. And the Eagles have yet to face a pair of receivers as big (Marshall is 6-foot-4, Jeffery 6-3) and as talented (Chicago is the only team with two 1,000-yard receivers) this season.

"They're going to come in and [show] us a different element to the game," Williams said. "Those guys are bigger. Those guys are stronger than most. Those guys run pretty decent routes. Those guys can go up and catch the ball. I think it's going to be a huge challenge to us in the secondary."

Eagles cornerbacks have used various coverages, but they have played softer off the line in many circumstances because Davis has been intent on limiting big plays (20 or more yards) over the top.

Williams and Bradley Fletcher don't exactly possess elite speed, so having them play off the line can help keep them from getting beaten deep. They both have solid ball skills and are above-average tacklers for cornerbacks, so they have the ability to limit big plays after the catch.

But if the pass rush isn't consistent enough, or if Williams and Fletcher are having off days, or if the officials aren't letting them grab as much, the scheme can implode as it did against the Vikings.

Eagles cornerbacks are often given some leeway on when they should play off receivers. Davis said there were times when he thought his defensive backs were too soft on Sunday. But the Vikings' packed formations also prevented press coverages when the Eagles were in zone defenses.

"When they were out, there were calls [when] we should have been tighter," Davis said. "There were calls [when] they were exactly where I wanted them. There was a little bit of a mix, different formations and groupings than they have shown in the past. Something we were adjusting to."

Early in the game, Williams was off the line 10 yards on first down and took a drop so deep that receiver Jarius Wright ran 13 yards past the sticks, caught the ball and turned upfield before the cornerback was in range to make a tackle. He gained 26 yards.

Fletcher was targeted 10 times and allowed eight catches for 134 yards. Most of those passes came when he was playing soft. He came up and made tackles almost every time, but Vikings receivers were often able to get a few extra yards after the catch.

Davis said he had his corners play more man-to-man press defense in the second half, but that didn't work entirely, either. Fletcher had solid man-to-man coverage on Wright in the third quarter, but the throw was on the money and the receiver made a great 42-yard catch down the sideline.

"Sometimes you run into buzz saws, man," Williams said, "and that's what it was."

Davis' plan all season has been to limit big pass plays, but the Eagles' numbers have been poor. They have allowed 55 pass plays of 20 yards or more - six on Sunday - and are tied for fifth worst in the league with the Packers.

"We gave up too many big plays," Davis said. "Three of them were thrown for over 20 yards. We did not make those plays. The others were thrown for under 20 and we missed tackles."

The Eagles also have been called for more defensive pass-interference penalties (14) than any other team in the NFL. Fletcher was flagged twice on Sunday. One cost the Eagles 30 yards.

Chip Kelly's offense is No. 1 in the NFL in big plays with 71. The Bears are 13th with 47. While Jeffery is more of a deep threat, Marshall can pick apart secondaries working intermediate routes. No matter how Davis plays his corners - off, up, wherever - it may not matter against the Bears.

"Just play tough, man," Williams said. "I don't know how to say it because I'm not the coordinator. I just know that I'm going to play my game and I'm going to show up on Sunday."