Clausen will become only the sixth quarterback in NFL history to start against the same team for two different clubs in one season. His only other start this year came against the Seahawks on Sept. 27 -- a forgettable 26-0 loss -- while he was with the Chicago Bears. Ten weeks later and on a new team, Clausen will face the NFL's No. 2 defense for a second time.
Clausen, 28, practiced with the Ravens' first-team offense all week, as Schaub was sidelined with a chest injury. It is not known whether Schaub, who was listed as questionable on the injury report, will be healthy enough to be Baltimore's No. 2 quarterback. Bryn Renner, who was out of football this season before joining the Ravens on Tuesday, was promoted from the practice squad Saturday.
"Jimmy is smart," Ravens coach John Harbaugh said. "He has been in this basic system before. He knows how to handle himself. He has played a lot of football, so he's fine."
This marks the third different starting quarterback in four weeks for the Ravens after Joe Flacco had started the previous 122 consecutive regular-season games, the fifth-longest streak in NFL history. Flacco tore two knee ligaments on Nov. 22, ending his season.
Clausen is 1-11 as an NFL starter. His only victory came in December 2010, when he was a rookie with the Carolina Panthers.
"He has really humbled himself over the years in terms of the things that he has had to go through in his NFL journey," said offensive coordinator Marc Trestman, who coached Clausen last season in Chicago. "He had a very difficult first year. The word out of Carolina was he handled himself in an exemplary fashion -- showed great leadership -- in a very, very difficult season. That showed up last year being around him, that the guys will rally around him. He's mentally tough and physically tough, and he has come in here under unusual circumstances and at an unusual time."