OAKLAND, Calif. – For most teams, the third exhibition game is the chance to give the starters their most time on the playing field during the preseason.

The Oakland Raiders are still figuring out who that will be at the most important position on the field heading into the third preseason game against the St. Louis Rams on Friday night.

Daunte Culpepper will be the third quarterback to start for Oakland this preseason, following Josh McCown and Andrew Walter.

“This competition, as I said a long time ago, it’s going to be about guys that make the right decisions,” coach Lane Kiffin said. “It’s not going to be about the biggest arm or the best stats. It’s going to be about the guys that make the right decision, put us in position to score and don’t give the ball to the other team.”

When he has held on to the snap – he has fumbled three center exchanges in two games – Culpepper has been the best at that, throwing a pair of touchdown passes last week against San Francisco without an interception.

Now he gets a chance with the entire first-team offense working against a first-team defense. Kiffin warned not to read too much into his pick as starter this week, saying he wanted to give all three of his quarterbacks a chance with the first team.

Kiffin said he’d like to pick his starter for the season opener after this game, but cautioned that he might wait until the exhibition finale next Thursday at Seattle. One of the three may not even make the team if the Raiders sign top draft pick JaMarcus Russell and decide to carry the usual three quarterbacks on the 53-man roster.

The key for Culpepper is to transform himself from the risk-taker he has been earlier in his career to a quarterback who controls the ball. Culpepper has thrown 137 touchdown passes, but also turned the ball over 124 times.

“This guy has been a big play-maker for his career, a ton of explosive plays, over 20-yard passes,” Kiffin said. “I told him from Day 1 that has to change, and that may sound weird to you guys, but he’s got to make smart decisions. We don’t want three-touchdown, three interception games.”

The Rams have no questions at quarterback where two-time Pro Bowler Marc Bulger signed a six-year, $65 million contract extension in July.

St. Louis also is expected to use a little more of star running back Steven Jackson, who got only one play last week against San Diego. In two preseason games, Jackson has only two catches for 8 yards.

He wasn’t used a lot last preseason either, with 17 carries and three receptions. However, he was fine once the season started, finishing with a career-high 1,528 yards rushing with 13 touchdowns and an NFL-leading 90 catches for 806 yards and three more scores.

Coach Scott Linehan said Jackson’s playing time will increase “a little bit” Friday, but second-round pick Brian Leonard is expected to get most of the carries as the Rams prepare for the season opener.

“I don’t think anyone in the league is going out and working their game plan in their opening game in these preseason games,” Linehan said. “On the same side, you’re working your base offense, defense and special teams because that’s really what’s going to win you games. You’re not keeping that a secret.”

Both teams are trying to figure out who their starting centers will be. Linehan said Brett Romberg will start Friday, but veteran Andy McCollum will also play as the job remains open.