What to watch: Broncos-49ers

The Broncos have given the requisite it-will-be-good-to-hit-somebody-else nuggets this week as the usual on-field grumpiness that comes with the third week of training camp has arrived.

But as they head into tonight's preseason opener in San Francisco here are a few things of note:

Position battles

The most heated in a starting lineup that is already largely spoken for are at running back, safety and middle linebacker.

At running back in-game performance and the ability to digest the long list of audibles in the offense -- as well as handle the business of pass protection -- will tip the scales.

But fantasy football owners dive in at your own risk because whether Ronnie Hillman or Montee Ball is the first back into the game during the regular season, every indication on the practice field right now is they're both going to get plenty of work in a variety of down-and-distance situations.

And the fact Knowshon Moreno and Jacob Hester are still more reliable than the youngsters in pass protection at the moment, makes the prospect of a running back-by-committee approach, and a large committee at that, a very distinct possibility unless Hillman or Ball simply puts the hammer down over the next four weeks.

And they know the score.

"We have a lot of guys,'' Hillman said. "Sure, I want to be the guy in there, but I know with Peyton Manning at quarterback, the guys who keep him from getting hit are going to play.''

"I think we all know where pass protection fits,'' Ball said. "I want to be the primary runner, I can't lie about that, but I also know we have the a lot of guys who want the same thing.''

At safety there will be a rotation of sorts as well when the team moves into the nickel and dime formations. But in the base defense Duke Ihenacho has made the long climb from undrafted free agent/practice squad guy in 2012 to working with the starters for much of the past two weeks.

The Broncos like Ihenacho's aggressiveness when he has a chance to make a play combined with good assignment discipline to get himself in the right spots. He now has to show that in games, because simply doing it in practice won't allow him to keep the job.

And at middle linebacker Stewart Bradley has made it a tight race with Nate Irving, perhaps tighter than many realize. Irving had the job all the way through offseason workouts, but Bradley has taken some snaps with the starters of late and it would be no surprise to see him get some work early against the 49ers, perhaps even get the start.

When Irving has had a bobble it usually is when he doesn't take on blocks head up in the run fits. When he tries to move around the block, he leaves a running lane.

The Broncos want consistent run fits and the guy who gives it to them will get the job.

The offensive line

It will bear watching how the Broncos line up in the offensive front and how long they leave Manning in the game if they are using multiple backups in the first group.

Right tackle Orlando Franklin (hip) won't play and left tackle Ryan Clady (shoulder) won't play. And given Ryan Lilja was signed out of retirement just a week ago after having both knee and toe surgeries earlier in the offseason, it would be a risk to play him too much against the 49ers.

That's despite the fact the Broncos rushed Lilja into the starting lineup -- at left guard one day and right guard the next -- this week following Franklin's injury. It all could leave things unsettled in front of Manning. Manning is scheduled to play a quarter at most, but the coaches have said Manning and other starters could depart earlier than that.

Offensive flow

It will be Adam Gase's first in-game run as offensive coordinator. Gase said he will call the game from the sideline instead of the pressbox to save a few seconds on the play clock with each play call.

Quarterbacks coach Greg Knapp will be in the booth.

Manning has said he believes Gase will be an efficient play-caller "who thinks ahead."

Gase has called plays in parts of games previously in his career, but this will be his first full game.