Stewart completed 18 of 29 passes for 303 yards and ran 10 times for 49 yards to lead a Steelers fightback from 21-7 behind. Jerome Bettis ran 24 times for 125 yards and moved within 106 yards of the club record for rushing yards in a season.
However, the Steelers were not assured of a play-off place until the New York Jets were upset 22-14 at home by Indianapolis, the NFL's bottom team with only two victories.
Pittsburgh also gained the lead of the AFC Central Division and a possible first-round bye when Jacksonville lost 26-20 to New England in a rematch of last year's AFC play-off final.
Drew Bledsoe threw for 234 yards and two touchdowns as the Patriots ended Jacksonville's home winning streak of 13 games despite the absence of their leading rusher Curtis Martin and receiver Terry Glenn.
Kansas City also earned a place in the play-offs when beating Oakland 30-0. With Denver's loss, the Chiefs and Denver, already through, now share the lead of the AFC West Division. The Chiefs have the edge in the chase for home advantage because they finish the regular season against two clubs with losing records, San Diego and New Orleans.
Seven play-off places are still at stake with each clubs having two games to play before the regular season ends on 22 December. San Francisco and the reigning Super Bowl champions Green Bay are already through. Green Bay beat Tampa Bay 17-6 in a key NFC Central Division game to join San Francisco, who beat Minnesota 28-17, with a first-round bye.Reuse content