The Denver Broncos have a monster task ahead of them on Monday night in the final NFL game of this extended Halloween weekend. The 3-3 Broncos, reeling after back-to-back losses to last-place teams, head to Kansas City to face the 5-2, division-leading Chiefs, themselves losers of two straight. The home team is favored by at least a touchdown in most books, and the number is moving in the wrong direction for Denver.

Given the overall direction they’ve been headed of late, a Broncos win in Kansas City feels like it would be one of the stranger things we’ve seen this NFL season.

With an offense that over the last two weeks has been about as exciting as a bathtub half-full of lukewarm water – one that last week was shut out for the first time in a quarter century and scored only 10 points the week prior – it’s understandable why Broncos Country is starting to freak that Denver’s once-hot start to this season could turn out to be more trick than treat.

When it comes to the Chiefs, things have been upside down for the Broncos ever since Bradley Roby picked up a Jamaal Charles fumble on the 21-yard line at Arrowhead Stadium with less than a minute on the clock on Sept. 17, 2015. Roby’s scoop and score sealed a 31-24 victory – at the time Denver’s seventh in a row against their division rival and fifth-straight win in Kansas City. Since that fumble (only the second time in Charles’ NFL career that he’s fumbled twice in a game), the Chiefs have outscored the Broncos 92-50 and handed Denver three consecutive losses head-to-head.

The Charles fumble opened the gate to a series of seriously strange games between the two sides that makes Monday night’s contest one of the more anticipated releases on the fall schedule.

After starting his Broncos tenure with seven consecutive victories against Kansas City, the beginning of the end of Peyton Manning‘s career took place against the Chiefs in their final meeting of 2015. Manning was intercepted four times and was eventually benched in favor of Brock Osweiler (on the same day Manning became the NFL’s career passing yards leader, no less). The offense produced no points with Manning on the field in a 29-13 loss.

We later learned the full extent of the foot injury (a torn plantar fascia) that hobbled Manning, but the future Hall of Famer’s performance at the time was mysteriously bad. Sure, Manning had been struggling off and on throughout parts of what would ultimately prove to be his final season, but it was becoming more and more clear that the mind was willing but the body might no longer be able.

The Broncos would, of course, summon the will to bounce back, earn the No. 1 seed in the AFC and go on to win Super Bowl 50. The Chiefs did their usual vanishing act in the postseason, losing to the Patriots in the divisional round, however their dominance over Denver was just beginning. Like a pollywog that had recently sprouted legs, the Chiefs were about to take a leap.

That win in Denver was the third of 10 in a row Kansas City would rattle off to end the 2015 regular season. They followed that with a 12-4 campaign in 2016 – including a two-game sweep of the Broncos – good enough to win the AFC West. The Chiefs, thanks the the mind of Andy Reid (and a little flair from the often under-appreciated head coach), boast an impressive 27-6 regular season record (28-8 including the postseason) over the last two calendar years.

Reid has been wizard when it comes to finding talent the Broncos (and the rest of the NFL, for that matter) have trouble matching up with. In their first meeting last season, Denver had no answer for Tyreek Hill. The flea-sized receiver/return man/do-it-all acrobat found the end zone three times for Kansas City: Once by land, once by air and once by kick return (coming after a safety, to make matters worse).

Yet for all the trouble Denver had with Hill (how do you spy someone with that kind of speed lined up in so many different formations, really?), Kansas City had just as much trouble stopping Trevor Siemian that Sunday night of the Thanksgiving weekend.

Siemian passed for a then-career-high 368 yards. (He surpassed that in a loss to the Giants in Week 6 this year.) His three touchdown passes were one shy of a career best. Siemian’s 125.6 passer rating for the game ranks second-best among games he has played start to finish. Still, strange things were afoot.

With less than 3:00 remaining, Denver had a more than a 93 percent chance of winning the game. Denver had scored a dagger touchdown to go up eight points, and Derek Wolfe had just sacked Alex Smith to open the ensuing drive.

Then, things got weirdo. The vaunted Denver defense – the one that had come up with critical stops so many times over the prior year and a half – couldn’t stop Kansas City. Facing second-and-17 from his own 18-yard line with no timeouts, Smith marched his team down the field like it was a parade down Maple Street. Hill found the end zone for the third time on the day and Smith would find Demetrius Harris for the two-point conversion with 12 seconds on the clock to send the game to overtime.

After the sides traded field goals on their first OT possessions, Gary Kubiak thought it wise to try and will a 65-yarder on Denver’s second possession of the extra period. Brandon McManus could not find a way and missed short. A few plays later, Cairo Santos booted a 34-yarder through the uprights to hand Denver a second loss in a row to their division rivals.

The Broncos’ trip to Arrowhead on Christmas Day last year was not nearly as dramatic as their post-Thanksgiving loss. Instead, Denver was drubbed 33-10 in a game that ultimately eliminated them from the playoffs. It was hardly a holly jolly way to spend the holiday. Tyreek Hill again gave Denver fits, breaking a 70-yard run that put the Broncos in a 14-0 hole they could not dig out of, no matter how they dug. (This year they’ll also have to contend with Kareem Hunt, KC’s running back equivalent to Hill.)

The strange thing about the Christmas game wasn’t so much the loss – Arrowhead has long haunted Denver in December – but rather the lopsided nature of the loss. Knowing their playoff fate hung in the balance, Denver came out looking like a team that would have rather been scarfing down a second helping of pie than one fighting in a last-ditch effort to keep their Super Bowl title defense hopes alive. Although, that was far from the biggest oddity in the last matchup between these two sides.

The strangest thing about the game had to be when Reid elected to run a trick play with under 2:00 remaining and the game well in hand. The only thing more surprising than Reid having nose tackle Dontari Poe throw a TD pass might have been to have Poe’s long-lost sister throw one (assuming he has one, that is). The point being, Reid emptied a trick from his bag at a completely unnecessary time, leaving the rest of the football world puzzled. (Think that play might have been useful on a failed two-point conversion that cost you a divisional round playoff game to Pittsburgh last season, Coach?)

If Broncos defensive coordinator Joe Woods is smart, the last thing he’ll show his unit ahead of Monday night’s game is that Poe touchdown. It was insult to injury. It was salt in the wound. It was the lasting memory from the loss that confirmed the season was a loss. It ought to have the Broncos defense hopping mad and ready to come out and give max effort.

They’re going to need to. The defense has to stop a Chiefs offense that is averaging 29.6 points per game. Denver’s offense, meanwhile, has scored just 42 points over their past four games (and 10 over their past two).

Yet, the Chiefs are only a touchdown (or so) favorite over the Broncos in Monday’s game.

It’s a rivalry game. It’s a division game. Could the Broncos pull the upset? Stranger things have happened.