Roethlisberger threw a 9-yard touchdown pass to Isaac Redman with 2:51 left after Polamalu forced a fumble with a sack of Joe Flacco, and the Steelers beat the Ravens Sunday night to gain sole possession of first place in the AFC North.
A fierce defensive battle turned when Polamalu hit Flacco's arm on a safety blitz. The loose ball was taken 19 yards by Lamarr Woodley to the Baltimore 9, setting up Pittsburgh's lone touchdown.
After throwing two incomplete passes, Roethlisberger dumped a short toss over the middle to Redman, who broke tackles by Dawan Landry and Jarret Johnson on his way to the end zone.
Baltimore's ensuing drive ended at the Pittsburgh 30 when Flacco bounced a fourth-down pass to Ed Dickson with 33 seconds remaining.
The victory left the Steelers (9-3) a game ahead of the Ravens (8-4) in the division and gave Pittsburgh a split of the season series.
Baltimore blew a fourth-quarter lead for the sixth time this season and had its eight-game home winning streak end.
Playing with a sprained right foot and overcoming a fierce pass rush, Roethlisberger went 22 for 38 for 253 yards. He has won six starts in a row against Baltimore and is 8-2 lifetime against the Ravens.
Flacco was 17 for 33 for 266 yards, but his fumble was the most decisive play of the game.
As is usually the case when the Steelers and Ravens meet, the trainers were kept busy tending to injured players.
Both starting tight ends were knocked out of the game. Baltimore's Todd Heap strained a hamstring on the first play from scrimmage and did not return.
Pittsburgh's Heath Miller suffered a concussion in the third quarter in a collision with Ravens cornerback Chris Carr.
The Steelers also lost right tackle Flozell Adams, who limped off the field in the third quarter.