OAKLAND -- Pride, an opportunity to avoid a losing season and a chance for a sweep of their archrivals and a winning division record ... all of these were at stake for the Broncos on Christmas Eve.

But their bid to salvage a rivalry win and build some season-ending momentum evaporated in a frustrating first half that saw the Raiders race to a 17-0 lead and hold on for a 27-14 win that sealed the Broncos' second consecutive losing season, ensuring the franchise's first back-to-back sub-.500 seasons since 1971-72.

The loss was different than the Broncos' previous five defeats, which came by a combined 19 points. This time, the Broncos trailed by 17 points on two separate occasions, never getting within single digits in the final two-and-a-half quarters.

"This loss felt a little bit like New York all over again," said safety Justin Simmons, referring to the 34-16 loss in Week 5. "It just felt like we kind of started off on the wrong foot and we just couldn't really bounce back from that. It's just frustrating."

Why did the Broncos fall?

Because of a 99-yard punt return

In one of the most unusual special-teams sequences in recent memory, the Raiders turned what should have been a downed punt inside the Oakland 5-yard line into a 99-yard touchdown that put the Raiders in front to stay just four minutes and 50 seconds into the game.

Colby Wadman blasted a 65-yard punt that bounced toward Oakland's goal line, and Isaac Yiadom appeared to have the punt covered. But the ball squirted out from under him, and Dwayne Harris alertly picked up the ball and sprinted up the right sideline.

It appeared on instant replay that Yiadom's right foot was on the goal line while he was in contact with the football, but after a review, referee Carl Cheffers ruled that the touchdown stood.

"The ball's down at the half-yard line and I guess we didn't have possession; as a consequence, he can pick it up and score with it," Head Coach Vance Joseph said. "That was a bizarre play."

It was part of a frustrating night for the Broncos' punt team.

Wadman got each of his first five punts inside the Oakland 15-yard line, but just one of them resulted in the Raiders starting inside their 20-yard line, as three skipped into the end zone and another ended in the aforementioned touchdown.

Harris' return ensured that the Broncos would not get the fast start they needed, and it started them down a path that resulted in a 17-point halftime deficit -- their largest in Oakland in 16 years.

Because the Broncos buried themselves in mistakes

Denver's penalty yardage in the first half wasn't excessive -- 36 yards on five infractions -- but it was the manner and timing of a pair of infractions that was most damaging. 

The first one -- a delay-of-game penalty -- cost the Broncos a chance to go for it on fourth-and-1 from the 50-yard line with 3:24 left in the first quarter. With the crowd roaring, the Broncos snapped the football and running back Phillip Lindsay scooted up the middle for a first down with room to spare, but the officials had blown their whistles through the din after the play clock reached zero, forcing the Broncos to punt. 

"We were going for it the whole time [on the fourth down] so I think [Case Keenum] got caught just getting out of the huddle and seeing the clock," Joseph said. "We have no excuses there. That ball's gotta get snapped." 

Early in the second quarter, the Broncos helped extend Oakland's 89-yard touchdown march by getting caught with 12 men on the field. The penalty turned a potential third-and-10 into second-and-5, and Oakland pounced, with Derek Carr hitting Jalen Richard for a 14-yard gain that moved the Raiders into Denver territory. Oakland scored five plays later.

Because they struggled to contain Doug Martin

The seventh-year running back came into the game averaging 4.0 yards per carry this season, but easily surpassed that Monday night, punctuating his 21-carry, 107-yard performance with a 24-yard touchdown run that doubled Oakland's lead with 8:01 remaining in the second quarter.

Oakland successfully used misdirection to confuse the Broncos on the touchdown, allowing Martin to gallop untouched down the right sideline. Two quarters later, a 14-yard Martin sweep moved the Raiders into a goal-to-go situation; the Raiders scored two plays later.

The Raiders' ground game was a non-factor when Martin was not involved; his teammates combined for just 12 yards on six non-kneeldown attempts. But Martin's work was more than enough to give Oakland a viable ground threat and keep the defense off balance.

Because Jordy Nelson extended Oakland's drives

None of Nelson's seven catches covered more than 16 yards, but five of them moved the chains -- including three on third downs, as he accounted for more than half of the Raiders' eight first downs through the air. Six of his first seven receptions also came on Oakland's three scoring drives.

Nelson's 12-yard catch 2:05 into the second quarter on second-and-5 moved the Raiders out of bad field position inside their 20-yard line, serving as a launching point for their 9-play, 89-yard march to Martin's touchdown run. His next two catches -- for 16 and 14 yards -- provided a majority of Oakland's yards on an 11-play, 55-yard drive that ended in a 43-yard Daniel Carlson field goal that pushed the Raiders' lead to 17-0 with 23 seconds left before halftime. 

After the Broncos narrowed the Raiders' lead back to two scores late in the third quarter, Nelson helped Oakland push it back to three, catching a pair of third-down receptions for 12 and 6 yards that set up Richard's 3-yard touchdown run 2:39 into the fourth quarter.

Because interceptions ended any hope of a comeback

After forcing a three-and-out immediately after Keenum's 19-yard touchdown pass to Courtland Sutton, the Broncos had a glimmer of hope for a Christmas miracle, taking over at their 10-yard line with 5:48 left, two timeouts remaining and a 24-14 deficit.

It took just two plays to extinguish that hope, as Keenum looked for Tim Patrick downfield in a thicket of Oakland defenders. Raiders safety Marcus Gilchrist intercepted the pass, setting the Raiders up at the Denver 31-yard line.

The Raiders didn't march to a touchdown, but they did force the Broncos to use a pair of timeouts on their three-play, 58-second possession before Daniel Carlson's 45-yard field goal extended the Raiders' lead to 27-14.

Denver's subsequent last-gasp drive collapsed under the weight of two penalties and an incompletion. It ended with an Erik Harris interception of Keenum on fourth-and-19, which allowed Oakland to run out the final 3:42 of the game, cementing the Broncos' third consecutive loss.