Peyton Manning ruined Dennis Allen’s homecoming Sunday when the Denver Broncos handed the Raiders their worst loss in this heated AFC West rivalry in a half-century.

Manning picked apart a secondary filled with backups, then walked off the field with a clean jersey and a smile a mile wide as the Broncos bounced back from back-to-back close losses with a resounding 37-6 rout of their archrival.

“Well, it was nothing more than an old-fashioned butt-whupping,” quarterback Carson Palmer said after the Raiders’ first loss in Denver in five seasons and their worst defeat in the series since Oct. 5, 1962, when they were humiliated 44-7 at old Bears Stadium.

Manning had his record-extending 65th 300-yard passing game, wasn’t sacked, intercepted or hurried and threw three touchdown passes while controlling the clock and watching Willis McGahee record his 32nd 100-yard rushing game, tops among active NFL players.

“They outcoached us, they outplayed us, they beat us in every phase of the game,” said Allen, Oakland’s first-year coach who was Denver’s defensive coordinator in 2011. “So, there’s not a lot positive that you can take from it.”

Allen pledged to use the upcoming bye week to evaluate everything from schemes to personnel.

“We’ve got to come up with a way to play better,” he said.

Oakland was without its two best cornerbacks in Ron Bartell (shoulder) and Shawntae Spencer (foot), so Pat Lee started at left cornerback and Michael Huff moved over to right cornerback with Matt Giordano sliding into his spot at free safety.

Picking and poking with short crossing routes and screen passes against a depleted Oakland defense, Manning finished with 338 yards and three scores.

For the second straight game, he didn’t throw an interception. Last week, he set a career high with 26 incompletions. This week, he threw eight, with 30 completions.

It proved too tough for the Raiders to face the four-time MVP without their top two cornerbacks.

“Well, it’s hard to play against Peyton Manning no matter what,” Allen said. “But we’ve got the guys that we have, and that’s who we’ve got to go out and play with and we’ve got to play at an NFL level. And so we’re not going to use injuries as a crutch.”

The Broncos (2-2) gained 101 more yards than the Raiders (1-3) in the first half, but only led 10-6 going into the locker room. But after the break, the Raiders were outscored 27-0, and the Broncos even didn’t punt all afternoon — only the fifth time that’s happened in franchise history.

“Well, I’m not exactly sure what that is, but we need to get it figured out because we haven’t played good in the third quarter,” Allen said.