Roethlisberger was 9 of 18 for 84 yards. Leftwich, playing for the first time in two years, was rusty in relief.
He completed 7 of 14 passes for 73 yards though he did produce a scoring drive early in the third quarter that gave the Steelers a 13-10 lead.
Cassel completed 11 of 26 passes for 154 yards for Kansas City. Cassel hit Tony Moeaki for 38 yards on the Chiefs’ second drive, setting up a 12-yard touchdown run by Charles to give Kansas City its first lead since a 7-3 victory over Denver in the 2011 regular-season finale.
The lead grew to 10-0 after Isaac Redman’s fumble deep in Pittsburgh territory led to a 22-yard field goal by Succop.
Like any brief flirtation with success for Kansas City, it didn’t last.
The Steelers drew even before halftime. Wallace atoned for an earlier drop by making a remarkable 7-yard touchdown grab in the corner of the end zone.
Playing against Todd Haley for the first time since firing him as head coach last December — Haley’s now the Steelers’ offensive coordinator — the Chiefs played with an energy they haven’t shown regularly this season.
Cassel — filling in for an injured Brady Quinn — said ‘‘without a doubt’’ it was the Chiefs’ most complete effort of the season. Crennel similarly was optimistic after the game.
‘‘We have a lot to get right so we can come back next week and be on the winning side of a game,’’ defensive tackle Dontari Poe said.
‘‘We were very energized as a team but we have to do that every week. It can’t just be this week; we have to come out next week and do that. We'll get it right.’’
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