Coming off their divisional home win over the Browns, the Ravens flew to Heinz Field for their Week 4 duel with the Pittsburgh Steelers, in their 3rd straight divisional game. Baltimore would trail early as Steelers running back Rashard Mendenhall picked up a 1-yard touchdown run.  The Ravens would take the lead in the second quarter as running back Willis McGahee got a 9-yard touchdown run, followed by kicker Billy Cundiff making a 33-yard field goal.  After a scoreless third quarter, Pittsburgh would get the lead again as Mendenhall made a 7-yard touchdown run in the fourth quarter.  Fortunately, Baltimore was able to go back ahead as quarterback Joe Flacco completed an 18-yard touchdown pass to wide receiver T. J. Houshmandzadeh with 32&#160;seconds remaining in regulation.  Middle linebacker Ray Lewis intercepted Pittsburgh backup quarterback Charlie Batch on the Steelers' final possession to end the game.. How many touchdown runs were there?