DENVER – Head coach Jack Del Rio had plenty of reasons to let his Raiders have it during the halftime break. The offense had minus-12 yards in the first half, an embarrassment unmatched in at least the last 25 years.

The Silver and Black were terrible offensively down just 12 points by the grace of excellent red-zone defense. Don’t forget this was a homecoming of sorts for Del Rio, who was Broncos defensive coordinator the past three seasons before this Raiders gig. His guys were laying an egg.

Del Rio didn’t yell or scream. He walked into the locker room with his signature swagger, remained calm and told his Raiders to carry on.

“He was confident we would make a push in the second half,” edge rusher Khalil Mack said. “He said that he believed in us. He didn’t let the first half get to him. He kept his poise, kept his swagger about him. Knowing that he believed in us was a real boost, and we went out and got that win by any means necessary.”

Del Rio set the tone for a second-half surge that produced a 15-12 victory over the Broncos at Sports Authority Field. It was the team’s first win over Denver since 2011.

[INSTANT REPLAY: Raiders rally back, pull off upset of Broncos]

The defense shut Denver out in the second half, spurned by Mack’s five sacks. One of them produced a safety. The offense kicked into gear, scoring a pair of key touchdowns that led to victory.

“Coach reminded us that we were only down by two scores, that a comeback was definitely doable if we fixed some things,” linebacker Ben Heeney said. “Before we left the field, we huddled up and he broke it by saying ‘Let’s win.’ That’s exactly what we did.”

Del Rio’s message this week, after last Sunday’s critical loss to Kansas City put the Raiders on the fringe of the playoff picture, was to play a true complete game. The Raiders didn’t do that. The first half was atrocious offensively, but they stuck with the plan, made some minor adjustments and turned the tables.

“The way we played in the first half is not a recipe for success,” quarterback Derek Carr said. “We just kept pushing through. We didn’t fix much. We just had to execute better, the way we know how. We knew they were going to make plays, and we could counter. We had great energy in the second half. There was a buzz on the sideline. We believed that we could comeback and win.”