In a surprising but potentially favorable development for the Ravens, Pittsburgh Steelers quarterback Ben Roethlisberger apparently will not start tonight's game at M&T; Bank Stadium because of concussion-related symptoms.
The Steelers decided Saturday that Roethlisberger will play only in an emergency. He will be the No. 3 quarterback, with former University of Pittsburgh starter Tyler Palko as Dixon's backup.
According to the Pittsburgh Post-Gazette, Steelers officials said doctors administered more tests to Roethlisberger on Saturday and will perform them again today. Roethlisberger, who faced similar tests all week, left last Sunday's game in Kansas City after taking a blow to the head. It marked his fourth concussion since 2006.
This is a major break for the Ravens, who go from playing Roethlisberger (who has a 6-2 record as a starting quarterback against the Ravens) to Dixon (who has thrown one pass in an NFL regular-season game).
The news that Roethlisberger might not play is stunning because Steelers coach Mike Tomlin said all week that the two-time Super Bowl-winning quarterback would start.
Roethlisberger, who was listed as questionable on Friday's injury report, also fully participated in every practice, according to the Steelers.
According to the Post-Gazette, Roethlisberger began having second thoughts Friday after he developed headaches following practices Wednesday and Thursday.
On Friday, Roethlisberger practiced but Dixon took most of the snaps.
Pittsburgh is expected to start Dixon because longtime backup quarterback Charlie Batch had already been declared out with a broken left wrist.
Dixon, 24, has played in just one NFL regular-season game - it came at the end of last season in a 31-0 win over the Browns on Dec. 28 - and the 6-foot-3, 209-pound quarterback completed his only pass for 3 yards.
The one-time Heisman Trophy candidate slid to the fifth round in 2008 (156th overall) because he tore the anterior cruciate ligament in his left knee during his senior season at Oregon.
During this year's preseason, Dixon completed 18 of 35 passes for 180 yards. In two 2008 preseason games, Dixon completed 12 of 24 passes. He ran for a 47-yard touchdown.
Palko, who will be Dixon's backup, was coach Dave Wannstedt's quarterback of choice at Pittsburgh when Joe Flacco was a backup there. Flacco then transferred to Delaware, where he developed into a first-round talent.
Fox Sports first reported that Roethlisberger wouldn't play against the Ravens.
The Associated Press contributed to this article.