Peyton Manning hasn't merely changed the way the Broncos offense goes about its business. He's changed the day-to-day expectations for the first-team defense, as well.

At last year's training camp, half of the snaps went to quarterbacks Tim Tebow and Brady Quinn. Both were prone to inconsistency and scattershot accuracy; Tebow's passes fluttered and often went low; Quinn threw tight spirals, but often overshot receivers. Kyle Orton was steady, but unspectacular, and Adam Weber was barely a rumor and didn't take any snaps against the first unit. For lengthy stretches, the defense dominated.

So far in this year's training camp, all of the first-team defense's work has come against Manning. And at times, they've been shredded. During Saturday's work, Manning went 10 of 12 in seven-on-seven periods. His completion percentage was lower in the team periods -- 60 percent -- but he's made liberal use of the deep ball, finding Andre Caldwell on Thursday and Eric Decker for big plays Friday and Saturday.

"Me and Peyton are not friends right now. Maybe after camp we can all think about that, but he's tough out there," said DE Elvis Dumervil, smiling. "We've got a lot of work to do. He's working. He's got the offense in sync, and they're moving pretty fast, so we've just got to keep working."

Decker's deep catch during team work came at Champ Bailey's expense up the right sideline, and it wasn't the first time the third-year receiver has beaten the perennial Pro Bowler.  Much of Decker's improvement stems from their practice-field duels, from which Decker said Bailey has provided "a lot" of advice.

"From coming off the ball, how to get off press coverage, what he looks for in knowing your routes, certain splits -- there's always little details that I think a lot of people don't understand," Decker said. "But when you're doing it every day, he can pick up on those things."

Bailey added: "[Decker is] like a different person. He's grown so much.  He wants to learn, he wants to be the best, and I love that about him."

On game days, the love between Denver's defense and offense will flow. But on the practice field, the defense is flummoxed trying to build off its improvement from dead last in yardage allowed in 2010 and 20th last year.

"Guys are eager and working hard, but we know we have a lot of work to do," said defensive coordinator Jack Del Rio. "We're challenging them physically and mentally. But I like the way the unit has started camp."

For up-to-the-minute Broncos updates, follow Andrew Mason on Twitter at @CBSSportsNFLDEN and @MaxBroncos.