Oakland Raiders outside linebacker Khalil Mack is on the verge of reaching some lofty career milestones for someone in his second NFL season.

Mack, the Raiders' first-round draft choice in 2014, leads the NFL with 15 sacks and needs one on Sunday at Kansas City to tie and two to break Derrick Burgess' single-season franchise record of 16, set in 2005.

Another sack or two could also help ensure Mack's joining Burgess as the only Raiders in franchise history to lead the NFL in sacks since it became an official statistic in 1982.

Not that he's counting.

"That's something we can probably talk about once I do it," said Mack, who leads Houston's J.J. Watt by a half-sack entering the final weekend of the regular season. "But at this time, a win would mean more than a sack title."

Mack, a leading contender for NFL Defensive Player of the Year, had four sacks as a rookie but surpassed that in a single game when he tied Hall of Famer Howie Long's franchise record with five sacks in a 15-12 upset of Denver on Dec. 13.

He's more than tripled his output from a year ago through a combination of experience and opportunity.

"It's been getting to grow within the game and know different situations and knowing different personnel groups and overall knowledge of the game," Mack said.

The Raiders have also given Mack more of a free leash under new coach Jack Del Rio than he had a year ago.

"I thought last year he had a lot of instances where he was really close [to some sacks]," Del Rio said, "and this year, he's been able to close the deal. Honestly, we've had him going forward a higher percentage of the time and he's had more opportunities."

And he keeps mastering the art of the sack with each game.

"Pass-rushers are always working on their craft," said Del Rio. "I played with Johnny Randle [at Minnesota]. Johnny, he'd be in a supermarket going down the aisle and he'd be pass-rushing on the old ladies trying to do their shopping. Guys that rush the quarterback, they never stop developing their skill level. I think certainly there's a lot of upside for young guy that's got a lot of talent that is learning the art of rushing the passer."

Part of the reason the Raiders have turned Mack loose this year is they lost pass-rushers Justin Tuck to injury in October, Aldon Smith to suspension in November and Mario Edwards to injury last week.

"Even with those guys playing, he might be the best one, and that speaks for itself because those are great players," said Chiefs left guard Jeff Allen, who will help double-team Mack in some situations.

"He was very disruptive last year, even when he had four sacks. This year he's doing the same thing, but he's getting there and creating havoc."

Mack recorded two sacks of Chiefs quarterback Alex Smith in the Raiders' 34-20 loss to Kansas City on Dec. 6 in Oakland. Although Chiefs passers have been sacked 45 times -- tied for fourth-most in the league -- Smith has proved to be elusive in recent weeks. He's rushed for 437 yards this season, fourth among quarterbacks, including 54 yards last week against Cleveland.

"That's a great challenge in itself," Mack said. "He has great escape ability, scramble ability, one of the more wiggly quarterbacks in the league. You've got to prepare for that throughout the week, it's no secret when he decides to get out, you've got to contain him."