PITTSBURGH — Ben Roethlisberger doesn’t need to bother with the math, not matter how simple the equation.

The Pittsburgh Steelers quarterback understands a win over Kansas City on Sunday sends his team back to the playoffs for the first time in three years. If Roethlisberger is being honest though, the postseason truly began a month ago.

“We’ve kind of had that mentality for the last couple weeks that it’s time to get hot and play our best football,” Roethlisberger said.

Anything less and the Steelers (9-5) will be home in January yet again. At least Pittsburgh has some wiggle room. A loss and Kansas City (8-6) will need a victory over San Diego in the regular season finale and plenty of help.

Quarterback Alex Smith would just as soon not have to spend the last Sunday of the year staring at a scoreboard during timeouts.

“You have been working hard to put yourself in this position,” Smith said. “You wanted the stages to get bigger and bigger and be more meaningful and here we are.”

How long the Chiefs stay there will depend on if they can slow down the NFL’s top-ranked offense, one led by a guy who knows a thing or two about the Chiefs.

Pittsburgh offensive coordinator Todd Haley spent two-plus seasons as Kansas City head coach from 2009-11, leading the Chiefs to an unlikely AFC West title in 2010 before it all fell apart.

Haley has resurrected his career calling plays for the Steelers, who are poised to lead the league in total yardage for only the second time in team history behind Roethlisberger, wide receiver Antonio Brown and running back Le’Veon Bell.

It’s heady territory for a franchise traditionally built from the defense up. Not so much anymore.

If anything, it’s the Chiefs who have adopted Pittsburgh’s formula for success.

Kansas City relies on steady if unflashy play from Smith, a one-two punch of Jamaal Charles and Knile Davis at running back and a swarming front seven led by outside linebacker Justin Houston, whose 17 sacks are tied for the NFL lead. Houston is close friends with Steelers linebacker Jarvis Jones, a bond forged when they played together at Georgia.

Houston serves as a mentor of sorts to Jones, who has dealt with injuries issues in his first two years in the league.

Jones describes Houston as “a freak” and one who happens to have something Jones has yet to experience: a playoff game. Jones can fix that problem on Sunday.

“It’s starting to come together,” Jones said. “A lot of us young guys, this is our first go-round with this. It’s why we’re here and we hope we’re ready.”

Other things to look for as the Chiefs search for their first victory in Pittsburgh since 1986.

Do it all

Charles has been one of the NFL’s most versatile backs in his seven seasons in the league. Pittsburgh’s Le’Veon Bell appears ready to join the group. Bell is second in the AFC in yards rushing and second in the NFL in total offense. The one thing Bell is still learning to do is finish drives.

That’s never been a problem for Charles, who has 14 total touchdowns.