Chris Boswell has tied an NFL record for most field goals in a playoff game.
Boswell's 43-yard field goal early in the third quarter was his fifth, tying a mark held by several others, including Adam Vinatieri. The kick gave Pittsburgh a 15-7 lead.
The Steelers signed Boswell early in the 2015 season with Shaun Suisham injured and Josh Scobee ineffective.
The chilly weather in Kansas City shouldn't be an issue for Boswell, who won the job in a kick off in miserable conditions at Heinz Field.
Boswell has made 50 of 57 field goals since signing with Pittsburgh. Earlier this season he kicked six field goals in a road win at Cincinnati.
The Steelers took the opening kickoff and drove right down the field behind quarterback Ben Roethlisberger and running back Le'Veon Bell to set up Chris Boswell's 22-yard field goal that gave the Steelers an early 3-0 lead.
Pittsburgh put up 22 points in the first quarter in the first meeting between the two teams in September, a 43-14 Steelers win.
The Chiefs are searching for their first home playoff victory since Joe Montana beat Pittsburgh in the wild-card round in the 1993 postseason.
Kansas City responded immediately. Alex Smith took the Chiefs 55 yards in six plays, finishing it with a little flip to Albert Wilson for a 5-yard touchdown that put the Chiefs up 7-3.
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