KANSAS CITY, Mo. — Everything was going about as well as it could have for the Pittsburgh Steelers.
The Kansas City Chiefs had punted three times, Patrick Mahomes threw his first career postseason interception at Arrowhead Stadium, and a gadget play resulted in a fumble-return touchdown for T.J. Watt.
The formula for an upset by the Steelers, who were the biggest underdogs of NFL Wild Card weekend at minus-12 1/2 points, was playing out perfectly.
Until it wasn’t.
The Chiefs rattled off three touchdowns in the final 5 minutes, 50 seconds before halftime and three more to start the second half — racking up touchdowns on six straight drives, including a stretch of five touchdowns in 11:31 of game time — en route to a 42-21 victory.
“It’s a good start, but we’re looking to do a lot more,” Travis Kelce, who notched his fourth straight 100-yard game in the playoffs, said.
The loss likely sends Steelers quarterback Ben Roethlisberger off into the NFL sunset.
With the win, Mahomes, who finished 30 of 39 for 404 yards with five touchdowns and an interception, stayed perfect in seven career home playoff games. He set a franchise record for passing yards and tied his own record for passing touchdowns in a postseason game.
The Chiefs, who had bludgeoned the Steelers 36-10 on Dec. 26, will host the Buffalo Bills at 5:30 p.m. next Sunday in a rematch of last season’s AFC Championship Game.
Buffalo beat Kansas City 38-20 on Oct. 10 at Arrowhead and is coming off a 47-17 win Saturday against New England.
“We understand this is the first step, but it was the most important game today and that’s the way our guys handled it,” Chiefs coach Andy Reid of advancing in the postseason said. “Now, we get ready for a good Buffalo team that’s coming in here.”
After falling behind 7-0, Mahomes threw a 4-yard touchdown to Jerick McKinnon, a 12-yard touchdown to Byron Pringle and a 48-yard touchdown to Travis Kelce to close out the second quarter.
Kelce finished with five catches for 108 yards receiving — giving him an NFL-record four straight 100-yard postseason games and seven overall, second most in NFL history behind only Jerry Rice (eight).
His touchdown with 13 seconds left was a deflating dagger for the offensively challenged Steelers, who punted on all seven first-half drives and managed only two first downs before intermission.
“We’ve got to start faster,” Kelce said. “We’ve got to be able to move the ball early on. Our defense did a great job.”
Kansas City continued to pour it on in the second half with some unusual (and fun) touchdowns.
“It’s my favorite time of the year, the playoffs, because those guys — Coach Reid, EB (offensive coordinator Eric Bieniemy), (quarterbacks coach Mike) Kafka — they go into the arsenal of finding these plays that we haven’t ran all season,” Mahomes said.
After a video review overturned a Tyreek Hill touchdown, Mahomes connected with Nick Allegretti, who is a guard by trade, on a tackle-eligible play for a 1-yard touchdown.
Less than a minute later, and after Willie Gay Jr. forced a Najee Harris fumble that Frank Clark recovered, Mahomes got Hill his touchdown with a 31-yard dime down the right sideline.
“It’s pretty cool when you have guys that are just making plays,” Mahomes said. “... It’s a great feeling as a quarterback.”
Pittsburgh pulled back a touchdown on Roethlisberger’s 13-yard dart to Diontae Johnson, but it was largely cosmetic.
Early in the fourth quarter, Kelce tossed his first career touchdown pass in the regular season or postseason on a 2-yard slant to Pringle, who finished with five catches for 37 yards and two touchdowns.
Roethlisberger added a 15-yard touchdown to James Washington midway through the fourth quarter, but it was far too little and far too late in a game that saw Kansas City outgain Pittsburgh 478-257.
“I thought our defense played tremendous,” Reid said. “We were aggressive on the back end, we were aggressive on the front (and) the linebackers did a great job of tackling. Just all around, scheme-wise, Spags put together a great game plan, the players executed and his coaches coached it up. So, it was a good look.”
With Clyde Edwards-Helaire sidelined and Darrel Williams limited with a toe injury, McKinnon made the most of his first career start with the Chiefs — totaling 142 yards from scrimmage, 12 carries for a game-high 61 yards and six catches for 81 yards.
Roethlisberger, who is expected to retire, finished 29 of 44 for 215 yards with two touchdowns and no interceptions
During the opening quarter-plus, Kansas City and Pittsburgh both struggled to establish a rhythm on offense.
The first five drives — three by the Steelers and two for the Chiefs — featured one first down as each resulted in punts, including Andy Reid’s decision to kick it away on fourth-and-1 at midfield.
The decision nearly paid off when Mecole Hardman Jr. returned the ensuing Pressley Harvin III punt 48 yards to the Pittsburgh 22-yard line.
Kansas City failed to take advantage of the field-position swing when presumptive NFL Defensive Player of the Year T.J. Watt batted Mahomes’ pass on a bootleg to the right into the air, allowing Devin Bush to pick off the errant throw.
It was the first interception Mahomes has thrown in seven career postseason games at Arrowhead Stadium.
The sad-sack showing by both offenses continued for three more drives, which also ended in punts before another costly Kansas City turnover.
Off a direct snap to Hardman, the exchange with running back Darrel Williams hit the turf. Williams scooped up the fumble only to have the ball get dislodged again when Cameron Heyward drilled him from behind.
Watt scooped up the fumble and returned it 26 yards for a touchdown to break the stalemate.
“We were all pissed off at ourselves,” Mahomes said. “We felt like we weren’t playing with enough energy. We felt like we weren’t playing at a high enough level and weren’t playing with enough urgency.”
Collectively, the Chiefs righted the ship without much prodding from the coaches, a product of the team's penchant for playoff rallies in recent seasons.
“I didn’t have to say much,” Reid said. “They knew. The players know better than anybody when there’s a screw up. But they beared down. Nobody was hanging their head.”
