Derek Carr strode confidently to the line to take his first snap from center as a quarterback for the Raiders ... and fumbled it.

"Any time a play doesn't work I'm not happy," Carr said after the Raiders had completed the first of five practice sessions over three days for their draft class, undrafted free agents and a handful of players invited on a tryout basis.

Carr, who seldom took a snap from under center in his last two years at Fresno State, had two more issues with exchanges before the day was done. He wore the No. 4 of his idol, Brett Favre, but wasn't taking the chances of a gunslinger, throwing mostly short, accurate passes while learning a new offense.

"There were no nerves, man," Carr said. "When it comes to football, it's fun. I was excited to finally get out and play football instead of getting in your underwear and running a 40 (yard dash)."

A sizable contingent of the media was from the Fresno area, where Carr's selection by the Raiders in the second round at No. 36 is the biggest thing going. Many of the questions posed to Raiders coach Dennis Allen had to do with Carr's spot in the pecking order and whether he could challenge Matt Schaub as the starter.

Allen made it clear Schaub was acquired to start but at the same time wasn't placing any limitations on Carr or what he could achieve as a rookie.