The Denver Broncos' injured backfield is beginning to get healthy.

Knowshon Moreno was back at practice Tuesday, one month after the starting running back hurt his right hamstring on the opening live drill of training camp.

Moreno said he was "80-some percent" healed.

"I think I'll be over it," said Moreno, who couldn't guarantee his availability for the Sept. 12 regular-season opener in Jacksonville. "At the same time, you never know with a hamstring."

Moreno likely won't play in the Broncos' preseason finale at Minnesota on Thursday night, a game in which Denver's starters are expected to play some, if not most, of the first quarter.

Still, it's significant that the Broncos' projected top three tailbacks — Moreno, Correll Buckhalter and LenDale White — are practicing together for the first time.

"In order to have a good season it all starts in practice," Buckhalter said. "So we're all happy to be out here."

Buckhalter returned to practice Aug. 24 and, at the time, was far away from the point where he could confidently say he was ready to initiate and take contact. But that week of work has done him good, and his anticipated role in the preseason finale now is welcomed.

"I'm definitely excited about the opportunity to go out there and play and establish that relationship with my linemen and get all of us on one accord so we can have a successful season," Buckhalter said.

White won't be around when the regular season starts because he's suspended four games by the NFL under its substance-abuse policy. So the Vikings game will be his last chance to play until October.

Less definitive is Moreno's status.

It's the second straight season he's missed most of August with a significant injury. He sprained his left medial collateral ligament in the 2009 preseason opener then carried the ball eight times in Week 1.

Moreno wasn't getting into specifics about his injury Tuesday and would only say he "feels good" and that his priority is regaining his stamina.

"I don't want to call it a setback. It was just an adversity he's got to push through and he's had to push through," coach Josh McDaniels said. "He's handled it the best he could and he's eager to get out there. I think that's where he is mentally."

Moreno was wearing an orange jersey at practice, alerting players to lay off on contact. He's been studying his playbook and attending meetings in addition to receiving treatment.

"He missed the same period of time last year in training camp so he's gone through this before. He started the season off and really hadn't played much in the preseason. We're kind of in the same boat," McDaniels said. "Hopefully we can start faster with him this year once we start playing the regular season, as soon as he's healthy."

In addition to Buckhalter's debut, the key to watch in the Vikings game is the continuing competition between rookie Tim Tebow and Brady Quinn for the backup quarterback job.

Quinn, acquired in the offseason, hasn't pulled away for the job and McDaniels called it a "competitive situation."

"Both players have done some good things. Both players have turned it over," McDaniels said. "Both players have been able to function in the 2-minute offense. And both players have plenty of room to improve. From that standpoint, I think this game will probably help us determine kind of where we see everything.

"But certainly I don't think either one of them has done so much that either guy has removed himself from the competition at all."

Quinn remains listed as the backup on the team's depth chart. But he's completed only 51.4 percent of his passes and has yet to throw a TD pass. His 55.1 rating is the worst on the team.

Tebow has been marginally better at 56.5 percent with a scoring toss to Eric Decker against Pittsburgh on Sunday night, along with an interception that led to a Steelers touchdown.

Quinn was asked afterward whether he felt he'd done enough to clinch the No. 2 job.

"It's honestly something I'm not focusing on, I think, until that situation presents itself," he said.