Giants running back David Wilson had cause for celebration during his break-through game against the Saints. (Bill Kostroun/Associated Press)

When the office door shut at the New York Giants’ practice facility earlier this week, running back David Wilson looked around to make sure nobody else could hear him.

A well-publicized fumble on the second carry of his NFL career led to a benching in his first NFL game and landed him in Coach Tom Coughlin’s doghouse, a memory Wilson has kept going in jest now that he has emerged as a key cog for the defending Super Bowl champions.

Just not when Coughlin is around.

“It’s pretty dark in there. They don’t even let you out to eat,” Wilson said, his words broken up by laughter. “The first game I went in the doghouse and probably had one link on my chain. Eventually I had a couple links and I was able to get my head out the doghouse a little bit. Now I think I’m on one of those retractable leashes. I get a little leeway until they push the lock button.”

The fun-loving first-round draft choice from Virginia Tech is back to his old antics, flashing his infectious smile all over the practice field, driving teammates and coaches crazy with back flips and, most importantly, infusing energy into the Giants at a time when they need to win their final two games of the regular season to guarantee an NFC playoff berth.

In a 52-27 win over the New Orleans Saints on Dec. 9, Wilson had his breakout game, setting a team record with 327 all-purpose yards, including 100 rushing yards, two touchdowns on the ground and a 97-yard kickoff return for a touchdown. He then received his first career NFL start on Sunday with starting running back Ahmad Bradshaw nursing a knee injury, although he gained only 55 yards in a 34-0 loss to the Atlanta Falcons.

Whether Wilson starts again this Sunday, when the Giants travel to Baltimore to face the Ravens, remains up in the air depending on Bradshaw’s health. But in search of validation after beginning his professional career in nightmarish fashion, Wilson is simply happy to have another chance.

Once he fumbled away his first opportunity, Wilson got his first taste of the relentless New York press corps. Even in the weeks after that first game, with Wilson’s relegated to kickoff return duty, he was hounded by questions about that first fumble.

Cornerback Jayron Hosley, who sits next to Wilson in the Giants’ locker room, could see the attention eating away at his former college teammate because “he wanted everybody to know that’s not the David he wanted to put out there or that’s not the David you’re gonna get.”

Eventually, with his playing time on offense limited mostly to mop-up duty, Wilson began to wonder about his own abilities, less than a year after setting school rushing records at Virginia Tech and earning ACC player of the year honors.

“Being a persistent guy, you want to keep seeing progress, but it was kind of stagnant for a while,” Wilson said. “You start to question: ‘Can I play football? I am good at this, right?’ But if I had gave up or threw the towel in and ‘I guess I’ll wait til next season,’ I wouldn’t have had that game [against New Orleans] because I wouldn’t be prepared for the opportunity,” Wilson said.

Wilson’s desire to earn back the trust of his teammates and coaches, and the surprising “toughness” he showed running the ball, impressed quarterback Eli Manning. It didn’t hurt that right when the Giants were looking for a spark — Bradshaw has been slowed by injuries all year and backup Andre Brown broke his fibula in a win over the Green Bay Packers last month — Wilson’s timing was impeccable.

“He’s focusing. He’s working hard, because he wants to be a guy that contributes and not the guy that prevents us,” Coughlin said of Wilson recently. “He’s going to be a target now. He’s going to have to know that, and so I hope he can handle it, and I have to believe he will.”

Back in an office at the Giants practice facility, Coughlin’s “leash” on his rookie running back is still apparent.

After all three of his touchdowns against the Saints, Wilson performed his trademark back flip, an image that made the covers of the New York tabloids. Except General Manager Jerry Reese, defensive lineman Justin Tuck and Coughlin, among others, weren’t exactly fans of it. “They pushed the lock button really quick,” said Wilson.

Just another lesson in a season he summed up in seven words.

“Don’t mess up,” Wilson cracked. “And definitely don’t fumble.”