Editor's note: This is the sixth in a series of stories previewing the Boise State football team by position. Tomorrow: quarterbacks.

Boise State tailbacks Jeremy Avery and D.J. Harper should be accustomed to the shadows. For the past two seasons, they were obscured by the star power of Ian Johnson.

And this fall, the co-starters have been a bit overlooked as fans and the media clamor to know where tailback-turned-defensive back Doug Martin fits into the offense.

But the fact that Martin - despite a terrific showing in last week's scrimmage - remains on defense is a sign of how much the Broncos expect from Avery and Harper, a pair of juniors who have waited patiently to take over a star-making position.

"You can kind of see it in their eyes that they feel this is their time to shine," said running backs coach Keith Bhonapha, who is in his first year. "I don't really think there's going to be a ton of pressure on them as far as being able to fill those shoes (of Johnson). I think those guys have been waiting to do that."

Johnson was arguably the biggest star in Broncos history - his number's record for jersey sales might never be touched. He set the WAC record for career rushing TDs and the school record for rushing yards in a season.

Avery and Harper backed up Johnson in 2007 and shared carries with him in 2008. They long ago proved they're ready for larger roles - Avery was the Broncos' MVP in the 2007 Hawaii Bowl and Harper rushed for 153 yards in a win at Fresno State as a true freshman.

"I'm totally comfortable," Avery said. "There will be a lot of new things you see out of me this year."

The job does come with some pressure, though. For starters, the Broncos are determined to regain their power ground game after rushing for their fewest yards since 2003 last year.

"We weren't consistent last year," Avery said. "We totally know this year we have to take that upon ourselves."

And then there's Martin, who will play nickel on defense but will be called upon if Avery or Harper gets injured or doesn't produce, coach Chris Petersen said. Avery and Harper sat out the scrimmage but have returned to practice, Petersen said.

"If both those guys are going and productive, then we'll keep (Martin) as an emergency-type guy," he said.

Avery is wickedly quick and surprisingly powerful for a 173-pound back. He rushed a little more than 100 times in each of the past two seasons, averaging 6.5 yards per carry in 2007 and 5.5 in 2008. Harper is a more powerful, more traditional runner. He has averaged 4.6 yards per carry in his career but hasn't gotten much work.

Both are burners - Harper is the team's fastest player (4.34-second 40-yard dash) and Avery is in the top five (sub-4.4). Both also are workhorses in the weight room.

In fact, they probably are more similar than they appear.

"You think of D.J. as a power guy, but then he's the fastest guy on the team," Bhonapha said. "You think of Jeremy as the quick guy, but he's strong, too."

Petersen says Avery "plays bigger than he is" - bringing a power runner's mentality to a scatback's body.

Harper, though, does have more of the bruising, linebacker-dragging element in his game.

"He keeps those knees driving," Petersen said, "and can get out of some things where you're going, 'How did he get out of that?' "

Like a legend's shadow.