KANSAS CITY - The Bengals offense committed the cardinal sin playing the high-flying offense of head coach Andy Reid's Chiefs and punted three times against the NFL's worst ranked defense as Kansas City built a 24-7 halftime lead Sunday night at Arrowhead Stadium.

And when one of those punts imploded for a fumble and another one sailed for a touchback with 1:13 left in the half, the Bengals defense couldn't stand up in a disheveled display that featured enough missed tackles of an entire season when Kansas City rolled to a staggering 319 yards in the first 30 minutes.

Chiefs quarterback Patrick Mahomes, the gun-slinging second-year player, began the night two touchdown passes away from Andrew Luck's NFL-leading 20 and he regained the lead with 1:55 left in the half on his third touchdown pass of the night to wide open tight end Demetrius Harris to give KC a 21-7 lead. It was a shockingly easy 17-yard play that summed up the night. Nobody touched Harris off the line as he got behind cornerback Dre Kirkpatrick and got wide open in the middle of Kirkpatrick, dropping defensive lineman Sam Hubbard and safety Shawn Williams.

But as badly the defense played, the inability of the offense to take control of the game against a Chiefs defense on pace to allow the most yards in NFL history was the most disturbing aspect of the half.

On the ensuing kickoff the Bengals got the ball at their 40 when the kick slithered out of bounds. But they couldn't run it against a defensive giving up 5.4 yards per carry and when wide receiver A.J. Green ended his monster 110-yard half with drop, another incompletion forced a punt and Mahomes' next four passes each got easy first downs on the way to a chip-shot field goal with eight seconds left in the half that made it 24-7.

So twice the Chiefs hit the Bengals in their Achilles' Heel. Now they've allowed points in the last two minutes of the first half in 17 of the last 24 games.

Mahomes cruised to 19 of 25 passing for 234 yards and a 144 passer rating. While Mahomes hit three receivers for at least 47 yards, all but eight of Bengals quarterback Andy Dalton's yards went to Green. Green had six of the 10 completions as Dalton went 10 of 19 with his touchdown pass going four yards to tight end C.J. Uzomah to cut it to 14-7 with 7:25 left in the half.

But the Bengals had no answers in all three phases. While Bengals running back Joe Mixon had 23 yards on nine carries, Mahomes took off three times for 42 yards.

The Chiefs went 95 yards on their first possession (when old friend Josh Shaw was called for a hold on the opening kickoff) and Kansas City's longest drive of the season was as bad as it sounds.

Missed tackles by safeties Jessie Bates and Williams began the drive on wide receiver Tyreek Hill's shimmying 27-yard catch and run. Cornerback William Jackson missed wide receiver Demarcus Robinson at the sticks for a first down and on third-and-two Mahomes fooled them badly when he kept the ball on a zone read and no one was near him on the right perimeter. Somewhere in there right end Michael Johnson had running back Kareem Hunt stopped for no gain, but he went too high and Hunt went low for six yards on his way to seven yards a shot in the first half.

Then Hunt really hit them in the gut. Kirkpatrick and a swarm looked like they had him for a two-yard loss, but Hunt emerged from the mess and then leaped over the 6-2 Bates to finish off a 21-yard run that won't be used in any defensive textbooks.

Mahomes then got an easy six-yard touchdown pass when he sprinted to the right edge in a two-way go, caught linebacker Hardy Nickerson in no man's land and flipped it over him to Hunt to give the Chiefs a 7-0 lead in the middle of the first quarter.

The Chiefs' second drive was more of the same for the defense. Missed tackles and looking about 10 miles per hour slower. Both happened on tight end Travis Kelce's 43-yard ramble down the left sideline. Slot cornerback Tony McRae missed the tackle on the edge and Bates, Williams and the linebackers couldn't get him.

But the drive was saved when Bengals head coach Marvin Lewis successfully challenged a completion into the red zone and the Chiefs were forced to try a 53-yard field goal. Harrison Butker cooperated with his first miss of the year when he hooked it.

It was at that point the Bengals had to take advantage and get back into the game. They had great field position at their own 43, but they did just the opposite and imploded.

Their tackles blew up the series. Right tackle Bobby Hart was called for a false start and then left tackle Cordy Glenn allowed pressure and Dalton's scramble couldn't get a desperation completion to Mixon.

Then the punt was a disaster. They appeared to try to run a fake, but personal punt protector Clayton Fejedelem dropped it and the Chiefs recovered at the Bengals 32.

The Chiefs didn't blink going up 14-0 with 13:18 left in the first half when they promptly parlayed two missed tackles by linebacker Vontaze Burfict into Hill's 16-yard completion (he caught it over the middle, avoided Burfict and then raced across the field out of bounds without being touched) and Hunt's 15-yard touchdown catch. Mahomes had pressure bearing down from his left and chucked it off his back foot to Hunt in a hurry and Burfict, wearing the defense's helmet microphone helmet, couldn't wrap him up.

The Bengals couldn't take advantage of scoring first to open the game. Mixon rolled for five yards on the first snap, but Green appeared to get mauled by cornerback Orlando Scandrick on a second-down incompletion and on third down Mixon couldn't get anywhere on a flip into the flat because two defenders were all over him.