Harrison then hit Ed Reed on a punt return, causing a fumble that led to Santonio Holmes' touchdown reception.
In the second quarter, Harrison sacked and stripped McNair again, driving the Ravens back until they were forced to punt from their 2-yard line. On the Ravens' next possession, Harrison intercepted a pass from McNair to wide receiver Demetrius Williams.
On the last series of the first half, Harrison and linebacker Clark Haggans combined for another sack as the Steelers had a 35-7 lead.
Harrison, who had not had more than one sack in a single game, finished the half with 2 1/2 sacks, two forced fumbles and an interception.
Rush 'D' still stout
The often-stated No. 1 priority of the Ravens' defense is stopping the run, and that was on display last night.
Steelers running back Willie Parker entered the game second in the NFL in rushing with 726 yards and had posted five 100-yard games this season.
Pittsburgh also had the league's top rushing attack entering Week 9.
Parker, however, has not enjoyed much success against the Ravens, who limited him 53 yards on 23 carries in two games last season.
Through three quarters last night, he had only 35 yards on 19 carries.
"That's just our style of football," strong safety Dawan Landry said last week. "You know that we always try to go out there and stop the run. Last year, we did a pretty good job of containing him. This year, he's off to a good start. We're trying to look to do the same thing this year.
"We're real confident this year because we know what we did last year, and we've been taking the run away from a lot of teams," Landry said. "We just have to keep doing that."
McAlister, Rolle out
As expected, Ravens starting cornerbacks Chris McAlister and Samari Rolle were deactivated last night, and Corey Ivy and Derrick Martin started in their places.
Rolle, who is dealing with a recurrence of an undisclosed illness that sidelined him for three games earlier this season, did not make the trip to Pittsburgh.
The team hoped that McAlister would be able to play despite a strained right knee, but there was only a 25 percent chance that the three-time Pro Bowl player would be able to suit up.
Tight ends Todd Heap (strained hamstring) and Daniel Wilcox (sprained toe) were not activated, meaning Quinn Sypniewski made his third start in the past four weeks. Heap has missed three of the past four games.
The Steelers deactivated two starters in defensive end Aaron Smith (knee) and safety Ryan Clark (spleen).
Defensive lineman Dwan Edwards, not Trevor Pryce, started alongside Kelly Gregg and Haloti Ngata. For Edwards, it was his fifth start in the past six games.
Pryce, who had not played since fracturing his left wrist in Week 2, might still be working off rust. That may explain how Roethlisberger was able to slip out of Pryce's sack attempt before finding Miller for a 17-yard touchdown pass in the first quarter.
Last night's captains for the Ravens were Ivy, Martin and nickel back David Pittman. As a show of support for Ivy, Martin and Pittman, the Ravens' players and coaches walked behind the captains and stood on the numbers on the field during the coin toss. ... The Ravens promoted tight end Lee Vickers to the active roster from the practice squad. To make room for Vickers, the team cut rookie linebacker Edgar Jones. ... The Ravens were 6-2 in the week after the bye during Billick's tenure. ... The Steelers haven't lost at home on Monday night since Oct. 14, 1991 when the New York Giants won, 23-20.