Jim Mone/Associated Press

Steelers rookie Rashard Mendenhall had an up-and-down game.

What we learned ...

Vikings D-line shows up: Minnesota's defensive line put pressure on QB Ben Roethlisberger, recording 2 sacks, knocking him down numerous times and focing him to rush throws. Defensive end Jared Allen didn't record a tackle, but did make his presence felt on a number of plays, including getting in between a potential screen pass to Willie Parker, forcing Roethlisberger to throw the ball into the ground.

Tarvaris Jackson sits: Jackson, the Vikings' starting QB who is still nursing a sprained knee, was supposed to play against the Steelers, but was held out of the game. Gus Frerotte started in his place and went 13-of-19 for 133 yards and an interception.

Steelers' running back looks like a rookie: Pittsburgh's first-round pick, running back Rashard Mendenhall was very inconsistent against the Vikings. While he did make some big plays, and was the game's leading rusher with 79 yards on 15 carries, Mendenhall fumbled the ball twice -- losing both -- including one on his second carry of the game.