As in a 256-pound, six-time Pro Bowler, gets-open-all-the-time, crushes hopes and dreams problem.
Yes, the Chiefs have Patrick Mahomes at quarterback and one of the planet's fastest humans in Tyreek Hill at wide receiver. Both have provided more than than their share of anguish for the Broncos during Kansas City's current 11-game win streak against Denver.
But more often than not it's been Kelce who has cratered the Broncos' defensive game plan in the most pivotal moments. And the Broncos' challenge Sunday night in Arrowhead Stadium (8:20 p.m. ET, NBC) will be to change that narrative without then letting everything else the Chiefs can do be the difference.
"They've got speed galore, they can throw it deep, they run good after the catch," Broncos coach Vic Fangio said. "It'll be an all-day sucker for everybody on defense."
Kelce has eight games in his career with at least 130 yards receiving and four of those have come against the Broncos at Arrowhead. And in those four games Kelce has turned 47 targets into 37 receptions.
The Broncos (6-5) have a little more speed, as well as a little more youth on defense than they've had in many of the teams' recent meetings. Four rookies played at least 40 snaps on defense in last Sunday's win over the Los Angeles Chargers and three of the rookies (Pat Surtain II, Baron Browning and Caden Sterns) started the game.
"It takes all kinds, I don't know if anybody has ever really shut him down," Broncos defensive coordinator Ed Donatell said of Kelce. "But you'll see Pat [Surtain] on him, you'll see Justin [Simmons] on him, you'll see Caden [Sterns] on him. We'll be sharing the duties on him, there will be times when he'll be doubled. It takes everybody."
Surtain's unique combination of speed, reach and size at the position (202 pounds) give the Broncos the kind of player they haven't had in the recent meetings. Back in August, former Broncos linebacker Von Miller said one of the biggest differences on defense this season was Surtain's potential to match up with Kelce and the Las Vegas Raiders tight end Darren Waller.
Asked Wednesday about the potential Surtain-Kelce matchup, Fangio said: "He could, but everybody has to be able to move around. ... It's a combination. When you get a tight end that's a really good receiver like he is, everybody automatically thinks you've got to put a [defensive back] on him. Well, he can outmuscle the [defensive backs] too, he's 260 pounds. You have to battle that part of it and you put a linebacker on him and you have to battle that this guy is really nifty as a receiver. And what compounds it his the karma him and Mahomes have together so it's just got to be a mix of guys."
The Surtain-Waller battle didn't really materialize during the Broncos' Oct. 17 loss to the Raiders when Waller finished with 59 yards on five receptions. In that game safety Kareem Jackson and cornerback Bryce Callahan, who was playing as the nickel cornerback in the five-defensive back look at the time, were matched on Waller most of the time.
Surtain handled Waller on two snaps, one of those an 8-yard reception. But the rookie, who has been in the starting lineup since Week 2, has embraced each task the Broncos have given him.
"Minimizing his big-play potential," Surtain said of the prospect of trying to cover Kelce. "Rerouting him, throw the timing off between him and quarterback, put hands on him."
The Chiefs, who are No. 2 in total offense in the league, tied for ninth in scoring offense and No. 1 in third-down success rate, have had some uncharacteristic turnover troubles this year. Only the New York Jets have had more turnovers than Kansas City's 22 and the Chiefs lead the league in lost fumbles (11).
Mahomes, who despite all of the handwringing about his play is fifth in the league in passing yards and tied for third in touchdowns, did have a seven-game stretch earlier this season when he threw 10 interceptions, but he has thrown one in the team's last three games before their bye last week.
"They're going to hit their big plays," Broncos safety Justin Simmons said. "From a defensive perspective, you've always got to have that next-play mentality, you can always change the game, the next play."