The Oakland Raiders rode the back of standout second-year pass-rusher Khalil Mack over the first-place Denver Broncos, winning 15-12 on Sunday.

Mack had a career-high five sacks, one which forced a key safety for Oakland.

Mack is the first player to record five sacks in a game since Aldon Smith did it for San Francisco in 2012, according to ESPN Stats & Information research. Smith signed with Oakland this season and is serving a one-year suspension.

Mack leads J.J. Watt by a half sack for the NFL lead. Watt and Houston plays New England on Sunday night. Mack, the No. 5 overall pick in 2014, had four sacks as a rookie.

Oakland is now 6-7, keeping its faint playoff hopes alive.

What were they thinking? In the third quarter, the Raiders were faced with a third down and less than a yard, and quarterback Derek Carr dropped back for a pass. He was sacked. Thus, a sure run situation turned into a punt in a key situation. In the fourth quarter, the Raiders went for two while leading by three. For some reason, they wanted to lead by five instead of four. Of course, Oakland didn’t convert and kept it a one-score game, leading 15-12. Completely stupid. Yes, long snapper Jon Condo was injured, but you must have a backup plan.

One reason to get excited: Mack is on a major tear. He had five sacks Sunday, including one that forced a safety. He has nine sacks in his past three games and has 14 sacks this season.

One reason to panic: The Raiders’ offense was awful in the first half.

Fantasy watch: Oakland rookie receiver Amari Cooper didn't make an impact. He was held without a catch for the first time in his career. Cooper is still 80 yards shy of becoming the team’s first 1,000-yard receiver since Randy Moss 10 years ago. Cooper, the No. 4 overall pick, has been good, but he hasn’t been perfect. According to Pro Football Focus research, Cooper has at least one drop in 1o of Oakland’s 13 games. Also, the site reports, Cooper hasn’t had more than 18 yards after the catch in a game in the past seven games.

Ouch: Starting right tackle Austin Howard left the game in the first half. Khalif Barnes replaced him. It is not known how badly Howard is hurt.