CHICAGO -- There may be no more graphic an illustration of just how the Green Bay Packers are stealthily evolving as a viable Super Bowl contender -- a team maturing in all facets of the game -- than what transpired late Sunday afternoon in the waning moments of a critical 20-12 victory over the miracle-mongering Chicago Bears.

With the upstart Bears driving for a potential game-tying touchdown, Chicago owning a first-and-10 at the Green Bay 21-yard line with 57 seconds remaining in the game and the specter of two straight overtime wins at Soldier Field intruding into the consciousness of players on both sides of the ball, the Packers' huddle suddenly grew very animated.

And very resolute as well.

	Bernardo Harris (55), Mike Wahle (68), and Darren Sharper (42) celebrate an incomplete pass late in the fourth quarter.

"You could tell guys were thinking, 'Oh, no, not again,' because of what the Bears did the last couple weeks here," said Green Bay free safety Darren Sharper. "I mean, that's a natural reaction, and you could see guys in their huddle were feeling like lightning might strike a third time. But we knew it was on the defense to stop them right there, to make sure they ran out of miracles, and we all got pretty vocal about that. It was like everyone in the huddle wanted the game on his shoulders. We had to stop them to prove something to them and something to ourselves."

When a fourth-and-4 pass from quarterback Jim Miller to an open James Allen was just slightly behind the Chicago tailback, who had swung out of the backfield and had a half-step on Packers defensive end John Thierry who had dropped into the left flat, the Green Bay defense had achieved its goal by securing the victory.

Suddenly the waves lapping up on the shores of nearby Lake Michigan were just plain water, instead of a special batch of liquid imported from Lourdes, and there would be no sequel this day of The Miracle on Lake Shore Drive.

By keeping the Bears out of the end zone and staving off overtime, the Packers moved into a tie for the division lead, with both teams 6-2 at the halfway point. But almost as significant, the young Green Bay defense took another giant step forward, and served notice it is an emerging unit that could ultimately determine how deep into the playoffs the Packers might proceed.

For as long as he draws breath, as long as he can still scramble around and buy time and then unleash a 30-yard laser off his back foot to an open wide receiver, the Packers will be Brett Favre's team. Anyone who doubts that need only pop in the video of Sunday's game, when Favre was the most obvious difference between the two NFC Central foes, firing two touchdown passes and rifling at least a half-dozen completions on passes that half the quarterbacks in the NFL wouldn't even have dared to throw.

But with the defense coming on now, the Packers appear to be a team capable of stealing a win even on those days when their three-time NFL most valuable player falls into one of his scattershot streaks. Indeed, this is a club that appears to possess its most well-rounded and complete roster in the last several seasons.

This is not, by any standard, an inexperienced defensive unit. Seven of the 11 starters are playing in their fifth season or more, the unit has but one rookie (defensive back Bhawoh Jue) who is contributing very little if anything at all, and the starters average 27.9 years of age and 6.2 seasons of NFL tenure. The man who was supposed to provide an outside pass rush, first-round draft choice Jamal Reynolds of Florida State, has yet to dress for a game.

But under second-year coordinator Ed Donatell, with some key insights from secondary coach Bob Slowik, ironically a former Chicago defensive coordinator, the Packers' defense clearly is more aggressive and more diverse. It doesn't hurt, either, to have three burgeoning stars in Sharper, cornerback Mike McKenzie and weakside linebacker Nate Wayne around.

Perhaps more than any of the other Green Bay defenders, those three players reflect the versatility and aggressiveness of the Packers, an outfit that now rates among the quickest units in the league. Strong safety LeRoy Butler, the 12th-year veteran graybeard who has subjugated his own role to allow the Packers to feature Sharper more, acknowledged after Sunday's game that no Packers team during his tenure has run as well as this one.

Said defensive tackle Santana Dotson: "We've got some young pups here who are doing a good job of making all of us feel younger again. They can get after people."

The third of three cornerbacks selected in succession by former general manager Ron Wolf in the 1999 draft, McKenzie has the size to muscle receivers off the ball and the deep speed to hang with opposing sprinters up the sideline. An afterthought during his first two seasons in Denver, the fluid-moving Wayne was acquired via a trade last year at the insistence of Donatell, who coached him as a Broncos assistant.

Wayne, who started zero games at Denver, started 13 in his first year with the Packers and provided Green Bay a productive two-way weakside linebacker to pair with Na'il Diggs on the strongside. But it is Sharper, who led the NFL with nine interceptions last season and earned his first Pro Bowl berth, who is becoming the defensive centerpiece.

A former college cornerback selected in the second round in 1997, Sharper struggled in his first three seasons before emerging as a legitimate playmaker in 2000. The Packers made him the highest-paid safety in history with a contract extension that kept Sharper off the unrestricted free agent market and, unlike many players who get the big money and never deliver, he quickly paid big dividends on the Green Bay investment.

On Sunday, he was the key to a Green Bay effort that limited the Chicago offense to four Paul Edinger field goals and never permitted the Bears to move any closer to the end zone than the Packers' 15-yard line. Sharper finished with eight tackles according to the official play-by-play, one forced fumble and a pass defensed.

To comprehend his impact on the game, though, one has to look inside the numbers. And that is what Chicago offensive right tackle James "Big Cat" Williams did after a loss that put the Bears in a precarious position, with two straight road games facing them now.

	“	Basically, they just loaded up the front (to stop the run). They sort of said, 'This is what we're doing, so let's see if you can beat us at it.' ... And we couldn't. ”
		— Jim Miller, Bears quarterback

"I don't know if they were guessing right, or they had a copy of the game plan, but they sent (Sharper) a lot on blitzes and he was always in the backfield," Williams said.

With a defense that characteristically plays six to eight players "in the box," the Packers crowded the line of scrimmage tightly on Sunday, cognizant of a Chicago aerial attack that rarely goes vertically up the field. While no Green Bay defender would allow it for attribution, the Packers simply weren't threatened by, and didn't respect, the Bears' endless series of short crossing routes, slip-screen passes and dumpoffs.

Given that, the Green Bay game plan revolved around stuffing Bears rookie tailback Anthony Thomas, the NFC's leading first-year rusher entering the game. And it became a game plan, as the contest wore on, that was plenty effective.

The Bears' second-round draft choice blasted for gains of 10 and 12 yards, both coming on runs to the weakside, on the first two snaps of the contest. In fact, he touched the ball on Chicago's first six plays and eight of the 13 offensive snaps in the opening possession.

But after some adjustments by the Packers -- players contending it was just a matter of better gap control than anything schematically-based -- the "A-Train" was derailed. On his final 20 carries of the game, Thomas totaled 23 yards. After the first quarter, he had 13 carries for only 18 yards. Eleven of his last 18 carries netted one yard or less.

"Basically, they just loaded up the front," said Bears quarterback Miller, who came back from a hip injury that kept him out of last Sunday's overtime victory over the Browns. "They sort of said, 'This is what we're doing, so let's see if you can beat us at it.' ... And we couldn't. They had the right calls too many times, and we didn't have enough right ones, plain and simple."

Much of that large disparity could be attributed to Sharper, who more than lived up to his surname in providing Green Bay a physical edge and who seemed to be inside the Bears' huddle when he wasn't in their backfield. Sharper takes tremendous pride in his regimen that includes hours of videotape scrutiny during the week of preparation.

He laughed when asked if he knew virtually every running play the Bears had called, but he certainly played like a man with inside knowledge -- or uncanny prescience.

By unofficial count, Sharper was used on eight run-blitzes by Donatell, who wanted to attack the Chicago offensive front. He had three tackles for minus-yardage, including a big six-yard loss on an inexplicable end-around play called by the Bears, and forced a fumble by Chicago fullback Daimon Shelton. On two other occasions, he forced plays back inside that resulted in losses.

It was, Sharper insisted, all in a day's work. But he also noted that he was particularly juiced for the game because of the attention paid lately to Bears free safety Mike Brown, the only man to return two interceptions for touchdowns in overtime and a defender who is being pushed by some people for Pro Bowl honors.

Sharper, who might never be any, well, sharper than he was on Sunday, took some joy from outplaying his Chicago counterpart. He was happier, however, about the victory in general. And, like most Packers defenders, thrilled about another game in which the unit proved that Favre doesn't have to be a one-man band for Green Bay to win.

By playing a nasty tune on the bruised Bears -- an anvil chorus, in fact, judging by some of the welts with which Chicago players exited the locker room -- the Packers' defense sent a loud message for the second half of the season.

"There's going to be a day, at some point, when Brett can't bail us out," Butler said. "It's going to be up to us to step up in those games. Today we showed we can do that."

Len Pasquarelli is a senior NFL writer for ESPN.com.