GREEN BAY — It wasn't that 11-yard touchdown catch against Cincinnati. It wasn't the 21-yard run against San Francisco. It wasn't even the go-ahead, 1-yard touchdown run against Denver.

No, Edgar Bennett realized the Green Bay Packers had something in undrafted rookie halfback Kregg Lumpkin not because of one of the many things Lumpkin has done well during the preseason, but because of his biggest mistake.

The Packers were trailing the Bengals 20-17 in the Aug. 11 exhibition opener at Lambeau Field, having pulled within a field goal on Lumpkin's aforementioned touchdown catch.

With 1 minutes, 54 seconds to play, the third-string offense took over at its 10-yard line. But after back-to-back completions got them out to the 26, the Packers had some momentum. On the next play, Matt Flynn threw across the middle to Lumpkin, who gained 9 yards ... and fumbled.

The Bengals recovered and iced the game. Lumpkin could be found on the bench, devastated.

"Very emotional. Very emotional," said Bennett, who had his own fumbling problems early in his playing career under coach Mike Holmgren. "That's what we want to see. You put the ball on the ground, it has to mean something to you. It has to matter. And certainly he was hard on himself, just as we were. He knows that cannot happen. But it was good to see how he responded."

Well-acquainted with missed opportunities after his promising college career at Georgia was derailed by injury, Lumpkin vowed to make the most of his second chance — if he got one.

"That's the cardinal sin for running backs. Not only did we have a chance to win the game, but fumbling the ball isn't me," Lumpkin said. "In college, you get another chance to redeem yourself. The NFL is cut-throat. You may not get another chance to get back out there."

But he did, and he enters Thursday night's preseason finale against Tennessee at Lambeau Field as the Packers' leading rusher (28 carries, 126 yards, 4.5-yard average) and second-leading scorer (12 points) behind kicker Mason Crosby.

"Lumpkin is a perfect example of what you're looking for in a rookie," Packers coach Mike McCarthy said Tuesday. "I think talent-wise, he brings a lot to the table, (and) he's improved every week. That's what you're looking for in rookies — to take advantage of their opportunity. He's put together a nice training camp."

Talented, when healthy

Lumpkin has always had talent.

He came out of Stephenson High School in Stone Mountain, Ga., ranked as the No. 2 prep running back in the country, and he played as a true freshman for the Bulldogs, rushing for 523 yards in 12 games and tying for the team lead in touchdowns (seven) in 2003.

But a torn ACL in his left knee on the first day of camp cost him the 2004 season, which he redshirted. He saw limited action in 2005 (the highlight being a 34-yard touchdown in the Sugar Bowl), and while he regained his starting job in 2006 (team-high 798 yards and six TDs in nine starts), a broken thumb and torn cartilage in his knee in 2007 left him with just 12 carries for 44 yards while Knowshon Moreno (the Bulldogs' starter this season) and Thomas Brown (sixth-round pick by Atlanta) passed him by.

"You get hurt, somebody else steps up," said Lumpkin, who had hoped to play in the Sugar Bowl but missed that game, too. "Every opportunity you get, you have to take advantage of it, because you never know if you'll get another one."

He got his opportunity with the Packers because the team's southeast scout, Brian Gutekunst, liked what he saw of him, as did college scouting director John Dorsey and general manager Ted Thompson.

After the draft, the Packers gave him a $4,000 signing bonus, but Thompson gave Lumpkin the ultimate compliment this week when asked about him.

"I think he's been pretty solid, pretty steady," Thompson said. "He's still learning, as all rookies are."

Translation: We really like the kid, and if we don't have room for him on the 53-man roster, we want him on our practice squad, so stop asking me about him.

Three RBs for two spots

Offensive coordinator Joe Philbin said the 5-foot-11, 228-pound Lumpkin is "a pretty good fit for this system, with his style of running. He's not a real dancer, he's got a little bit of straight-line (speed), which I think fits us well. He's got nice size, he's a good-looking guy in pads. He looks like a running back. He's got some good attributes, no question. We've got to keep looking at him to see if he can produce on a consistent level. He's certainly produced when he's been in there."

Now, to earn a roster berth, Lumpkin will have to produce one more time, on Thursday night. He's competing with veterans Noah Herron and Vernand Morency for one of the two halfback spots behind starter Ryan Grant and backup Brandon Jackson.

"I don't think I've surprised myself. I feel confident in what I'm doing, and I'm just going out there doing it," Lumpkin said. "But I've got to stay hungry. I can't get complacent. All I can do is hope and pray that the situation is revealed and I'll be somewhere."