TERRE HAUTE, Ind. -- Joseph Addai seems like the perfect student.
When the Indianapolis Colts wanted their first-round pick to stick around for summer workouts, he didn't give his scheduled trading card photo shoot a second thought. When Peyton Manning sent a congratulatory text message to him for signing his contract, Addai already was busy studying the playbook.
And when he got his first big crowd reaction at training camp, Addai reacted like a veteran by downplaying it. He insists he's not sucking up. Instead, he'd rather prove he's the perfect replacement for Edgerrin James.
"I'm not his coach, and I don't want to be his coach. I want to be a resource to him," said Manning, the NFL's two-time MVP. "The thing I like is he asks questions, and he's not afraid to ask questions. He's always asking me `why?"
In the Colts' offense, the why question is a common refrain.
With their complex passing scheme, liberal use of the no-huddle offense and the constant changes at the line of scrimmage, learning the system can be a huge challenge for a rookie.
Just ask Reggie Wayne, who caught just 27 passes his first year in Indy. Or Dallas Clark, who had 29 receptions in 10 games as a rookie.
The difference is Wayne and Clark didn't come to Indianapolis under nearly as much scrutiny as Addai.
When the Colts let James, the franchise's career rushing leader, leave as a free agent in March, the Colts were content to let Dominic Rhodes fill the void. Then they drafted Addai with the 30th overall pick in April and the comparisons with James began in earnest.
They're nearly identical in stature -- James was 6-foot, 214 pounds; Addai is 5-11, 214. Both played in the South: James at Miami; Addai at LSU. As good as James was running the ball, he was an even more cherished blocker. Addai entered the draft rated by many as the best pass-blocking back available.
Yet the soft-spoken Addai would rather keep his studious reputation than talk about it.
"It's a learning process, and I'm trying to spend time in the playbook," he said. "Every chance I get, I go back and read and revise what I did."
On the field, the Colts are trying to ease the pressure on Addai.
Coach Tony Dungy and president Bill Polian have both cautioned against the inevitable comparisons, and team officials still expect Rhodes and Addai to split carries this season.
Addai has been impressive at practice.
He's repeatedly demonstrated that he can hit holes quickly and accelerate past one of the league's fastest defenses. He's also proven he can make fluid changes, catch passes and, most important, pick up blitzers -- all essential ingredients to the Colts' success.
"When you come in here with a quarterback as seasoned as Peyton, you better be ready for all those changes," said running backs coach Gene Huey. "Taking all of those interlocking things, you're able to execute freely and it frees you up to be impressive."
What Addai must prove now is that he can excel in games, too.
He barely got a chance in Thursday night's preseason opener at St. Louis, where he carried only three times for three yards. He also caught two passes for 12 yards, but it was enough to earn Dungy's praise.
Addai will likely get more opportunities in Sunday's preseason home opener against defending NFC champion Seattle.
"We know these guys can run," Dungy said. "So it was good to see Dominic and Joseph running pass routes and picking up the blocks. Both those guys did well."
It's not clear yet if either player has the inside track to becoming the workhorse back.
Rhodes spent the past five seasons as James' primary backup and rushed for 1,104 yards in the final 10 games of his rookie season when James went down with a torn ACL. That was an NFL record for an undrafted rookie.
Since then, Rhodes' battle against injuries and James' return limited him to a paltry 130 carries for 529 yards in the last three years. So he's eager to prove he can start in the NFL.
Addai, however, is bigger and has more upside.
"Joseph has been good," Dungy said. "One thing is that he's not gotten flustered with the audible system."
Addai knows what it will take to win the job: more studying.
"It's kind of getting easier, but I wouldn't say it's easy," he said. "I get a lot of help from the running backs. I'm learning a lot."