Updated at 10 a.m. with Steelers announcing Roethlisberger is out

It isn’t just Ben Roethlisberger’s injured shoulder that’s dealing him fits and will sideline the Pittsburgh Steelers quarterback Sunday night against the Baltimore Ravens.

Roethlisberger also hurt a rib in the Monday night game against the Kansas City Chiefs, an injury that the Pittsburgh Post-Gazette reports “could also be a serious problem.” Roethlisberger, Jay Glazer of Fox Sports first reported, will not play Sunday, with Byron Leftwich getting his first start since Sept. 27, 2009.

Coach Mike Tomlin did not mention the rib injury Tuesday, saying only that Roethlisberger has a sprain of the sternoclavicular joint that connects the sternum and collarbone. Nor did Tomlin mention the severity of the sprain and whether it will keep him out multiple weeks. Roethlisberger was hurt early in the third quarter of the Steelers’ 16-13 overtime victory when he was sacked by linebacker Justin Houston. He left the game and headed to a hospital for an MRI and was to undergo another one Tuesday.

An SC sprain is relatively rare in football. That’s the injury that ended Brett Favre’s consecutive-games streak when he was playing for the Minnesota Vikings in 2010. Favre suffered the injury Dec. 5 and played next on Dec. 20. St. Louis Rams wide receiver Danny Amendola suffered the same injury Oct. 4 and was out until Sunday, when he played against the San Francisco 49ers.

Tomlin indicated Tuesday that Leftwich would take snaps with the first team during practice this week. During the Roethlisberger era in Pittsburgh, the Steelers are 0-4 against the Ravens without him. With him, they’re 9-5. The teams play twice in the next three weeks.

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