Roethlisberger, suspended by the NFL for the first four games of the season, was not chosen a Steelers captain in a vote by his teammates. He was selected the previous two seasons.
Wide receiver Hines Ward was voted as an offensive captain for the sixth season, while tight end Heath Miller was chosen for the first time.
"The captain's not just what you do on the field, it's what you do off the field," Ward said Monday. "Heath lives here (at the training facility), he's constantly here during coaching sessions and offseason workouts. It's well deserved."
Linebacker James Farrior will be the lone defensive captain, the seventh time he was selected. James Harrison was not selected after being chosen last year.
The special teams captain is linebacker Keyaron Fox, succeeding kicker Jeff Reed.
Roethlisberger missed part of the team's offseason workouts following allegations he sexually assaulted a Georgia college student in March, although he wasn't charged.
Roethlisberger initially was suspended by the NFL for six games, but Commissioner Roger Goodell reduced that to four games on Thursday because the quarterback has stayed out of trouble and kept to a program mandated by the league.
Ward doesn't think the Steelers intentionally slighted Roethlisberger by not choosing him a captain.
"Ben's our quarterback," Ward said. "That in itself, he's the leader of this team."
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"Until he (Roethlisberger) gets back, we have to do it by any means necessary, the same way you deal with injuries," Ward said.
The Steelers already are dealing with Leftwich's knee injury, which will keep him sidelined indefinitely -- possibly for the length of Roethlisberger's suspension. Leftwich was expected to start while Roethlisberger was out.
Dixon, a third-year player from Oregon, has made only one NFL start, throwing for a touchdown and running for another during an overtime loss in Baltimore last season.
Dixon and longtime backup Charlie Batch are the lone two healthy quarterbacks eligible to play. Batch has played with Pittsburgh since 2002 and has an intimate knowledge of their playbook, but has thrown only two passes since 2007 while getting injured each of the last two seasons.
Because Monday's session was an extra workout on a day the team normally doesn't practice, the Steelers may not reveal their starter until Wednesday's practice. Normally, the starters practice together on Wednesdays and Thursdays.
Copyright 2010 by The Associated Press