Tomlin said he picked Dixon over longtime backup Charlie Batch because of Dixon's strong performance in the preseason. Ben Roethlisberger is serving his four-game suspension for violating the NFL's personal conduct policy, while Byron Leftwich is out indefinitely with a sprained left knee ligament.
"It's an honor, obviously. The ultimate for a quarterback is to be the starter," Dixon said Monday. "It's every quarterback's dream to be a starter in the National Football League. My number is called now, and I'm going to have fun with it. I'm happy, but there's a lot of work to be done."
Leftwich, reacquired by Pittsburgh during an April trade, was expected to start while Roethlisberger was out, but sprained his left medial collateral ligament Thursday against Carolina. Dixon, a third-year player from Oregon, threw for a touchdown and ran for another during an overtime loss in Baltimore last season when Roethlisberger was out with a concussion.
Dixon took snaps with the starters during the Steelers' first practice of the week Monday. Dixon is an excellent runner and has a good throwing arm, but Batch is much more experienced and has an intimate knowledge of the playbook.
"Dennis has had a very productive preseason and training camp," Tomlin said. "He went into the training camp as a young guy, second in the pecking order behind Byron Leftwich. He did a nice job and made it extremely competitive. He waged a battle and got some first-team reps in some preseason games. Largely, we've been very impressed with how he's handled himself in game situations."
Dixon got much of the work with the starters Aug. 29 in Denver, hurting his chances of beating out Leftwich by throwing two interceptions during a 34-17 loss.
Batch has played with Pittsburgh since 2002, but has thrown only two passes since 2007 while getting injured each of the past two seasons. He was the No. 4 QB during training camp, and his lack of time with the starters during camp and in the exhibition games hurt his chances of starting.
"There was a specific pecking order in camp, and Charlie's durability or lack of durability added into it," Tomlin said. "This is a guy who's been on IR [injured reserve] a little bit the past couple years, but he also requires very few snaps to be prepared to play football at an acceptable level."
Information from The Associated Press was used in this report.