By Steve Keating

CHICAGO (Reuters) - The Chicago Bears bandwagon was getting a little crowded Tuesday after the Windy City woke up to find their team unbeaten and sitting atop the NFC standings.

What would have seemed like a dream just three weeks ago has turned into pinch-yourself reality for Chicago supporters after the Bears (3-0) validated their perfect start with a scrappy 20-17 win over Green Bay Packers on Monday.

The victory enabled the Bears to join a pair of AFC teams, the Kansas City Chiefs and Pittsburgh Steelers, as the only unbeaten teams in the NFL.

A tight season-opening win over the Detroit Lions followed by a victory over the Dallas Cowboys had generated cautious optimism but it was a win over their NFC North rivals, the Packers, that had a Bears buzz blowing through the city.

The showdown with Green Bay, tipped as a Super Bowl favorite since training camp, was viewed as the acid test for the Bears, who were considered longshots just to make the playoffs when the season opened.

Then it's home games against two inconsistent teams, Seattle and Washington, followed by a trip to Toronto to take on another club that has yet to taste victory, the Buffalo Bills.

"Every week is a big victory, every week is a big game," said Bears linebacker Lance Briggs. "Right now we sit alone atop the NFC North.

"This is where we want to be and we're going to have to fight to stay there."

In a many areas the Bears were badly outplayed by the Packers, who inflicted as much damage on themselves with a franchise record 18 penalties.

But the Bears, playing with the type of grit that was the trademark of the champion Monsters of Midway of the 1940s, keep finding ways to win.

"I'd rather have an ugly win than an ugly loss," said Bears defensive leader linebacker Brian Urlacher. "They had a lot of yards, but yards don't mean crap, points do.

"We showed a lot of character. Our guys never gave up."

The 180th meeting between the NFL's two most storied franchises brought out the best in the Bears and the worst in the Packers, who self-destructed with 152 yards in penalties.

The first meeting between the Bears and Packers featured a fist fight and in the 179 clashes since nothing has happened to defuse the bitter rivalry that is as old as the NFL itself.

When the Bears hired Lovie Smith as coach in 2004, he said his team would have three goals each season; win the NFC North, win the Super Bowl and beat the Packers.

"Our series with the Packers is a great rivalry game," said Smith. "Most of them end up going right down to the end like that one.

"I thought our guys played hard for 60 minutes and I know that is old coach talk but they did...the guys just kept fighting through.

"I just know they are laying it on the line, they're physical. Tonight, when we were honoring the Monsters of the Midway, it's just good to see a team play 60 minutes of ball. The guys just weren't going to be denied."

(Editing by Steve Ginsburg)