GREEN BAY -- After a feel-good beginning to the season that exceeded expectations -- quarterback Aaron Rodgers' near-flawless start replacing a legend, back-to-back victories over divisional opponents, relative good health -- the Green Bay Packers learned from the Dallas Cowboys Sunday night at Lambeau Field how far they have to go before they're a legitimate Super Bowl contender.

Unable to stop the run or the big play defensively, unable to get their previously explosive offense in gear and unable to generate any semblance of momentum throughout the night, the Packers proved no match for the NFC favorites, falling 27-16 before a Lambeau Field regular-season record crowd of 71,113 Sunday night.

"You never want to lose, no doubt about it. It's frustrating. It's disappointing," said Packers coach Mike McCarthy, whose team was outgained 453-334. "It was a big game. It was a great measuring stick for our football team.

"And I'll tell you exactly what I told them: The Dallas Cowboys are further ahead than we are right now. That's the facts and that's Week 3. How far ahead? Time will answer that question. We have work to do, we'll continue to do it."

On defense, Green Bay (2-1) watched as the Cowboys' two-headed running attack of Marion Barber (28 carries, 142 yards) and Felix Jones (six carries, 76 yards, including a 60-yard touchdown) ran roughshod over them; tight ends Jason Witten (seven catches, 67 yards) and Martellus Bennett (37-yard catch) and wide receiver Miles Austin (two catches for 115 yards -- a 63-yard catch to set up one touchdown, followed by a 52-yard TD catch of his own) made up for a shut-down Terrell Owens; and Dallas (3-0) asserted its early-season NFC dominance.

On offense, the Dallas pass rush forced the Packers into frequent max-protect calls, leaving Rodgers (22-for-39, 290 yards) few open receivers downfield and still often running for his life (five sacks) on the first rough night of his young starting career. The running game went next to nowhere (Ryan Grant had 54 yards on 13 carries), and wide receiver Greg Jennings (career-high eight catches for 115 yards) was the only consistent offensive threat all night.

And adding injury to insult, the Packers played virtually the entire game without starting cornerback Al Harris, who missed most of the first half taking IVs because of cramping problems and did not return after halftime after team doctors found blood in his urine, and were forced to play with two backup safeties after Nick Collins (back) joined inactive Atari Bigby (hamstring) on the sidelines. No. 3 wide receiver James Jones (knee) also was sidelined.

"You're not going to beat a good team like that with the mistakes that we made," Packers left guard Daryn Colledge said. "They're a very good team, and if you're going to match their scoring, you have to match their intensity. And we didn't do that."

The night seemed cursed from the very start, as James Jones hurt his knee on the first play of the game, and Grant fumbled on the second play from scrimmage when he was hit by Adam Jones. "Pacman" returned the fumble 21 yards to set up Nick Folk's 25-yard field goal for a 3-0 Dallas lead.

"Not the way you want to start," Grant said. "That's inexcusable."

The Packers got the three points back on the ensuing possession on Mason Crosby's 36-yard field goal, then took a 6-3 lead after Nick Collins' end-zone interception and 61-yard return led to another Crosby kick.

But Felix Jones broke free around left end, past defensive end Mike Montgomery and through cornerback Charles Woodson's arm tackle for his 60-yard TD, and Dallas tacked on another Folk field goal just before halftime.

The Packers pulled within 13-9 on Crosby's third field goal on their first possession of the second half, but after that, the Cowboys' passing game came to life -- even with Woodson rendering Owens (two catches, 17 yards) a non-factor all night.

Late in the third quarter, quarterback Tony Romo found Austin roaming free across the middle of the field, and Austin's 63-yard catch-and-run set up a 2-yard TD run by Barber to make it 20-9. Romo, on a third-and-20 play from the Dallas 48-yard line, then hit Austin for a 52-yard TD with 9 minutes, 9 seconds left in the game for a 27-9 lead.

The Packers finally reached the end zone with 2:11 left to play when Rodgers scored on a 1-yard quarterback sneak.

"(The Cowboys) did a nice job tonight. You've got to give them credit," Rodgers said. "Their defensive game plan was very solid. They did a nice job containing (me) when there wasn't anybody open. They had solid guys rushing the passer and did a nice job. I didn't throw the ball as well as I wanted to, unfortunately.

"But we're going to learn from this. We're going to watch the film tomorrow and get better and hopefully see them down the road at some point."