Corey Nelson led the star-studded Denver Broncos in tackles last week after linebacker Danny Trevathan left the game against the New York Jets with a broken left leg.

Nelson won't blame anybody for asking, "Corey who?"

He didn't expect to hear his name called on draft day, much less over and over on the public address system at MetLife Stadium with his seven-tackle performance.

His senior season at Oklahoma ended with a torn left pectoral muscle in the Sooners' fifth game, and he was denied a medical hardship by the NCAA for another year of eligibility.

So, he earned his degree in communications and started thinking maybe he could make a living talking about football instead of playing it.

"I didn't even know if I was going to play NFL ball or even if this was a future for me," Nelson said. "Just the way the season ended how I didn't play (much). And I didn't get that much burn my junior season just because a whole new (defensive coordinator) came in. I didn't really play that much my college career. And I just thought nobody knew about me."

When other players were crisscrossing the country on visits to NFL teams, Nelson was doing crisscross puzzles.

"I didn't go on any visits," he said.

The Broncos, who take a 4-1 record into Sunday night's showdown with San Francisco (4-2), selected Nelson with the 242nd overall draft pick, 14 spots away from "Mr. Irrelevant."

Getting drafted was one thing. Making a team that had been hyperactive in free agency and which had few holes following a Super Bowl appearance was yet another hurdle facing Nelson.

He spent much of August wondering if he had what it took to make the 53-man roster. That answer finally came in his final audition in the Broncos' fourth preseason game, at Dallas.

"That's when I realized I can really do this," he said.

Like many late-round rookies, Nelson made his mark on fourth down at first.

"Corey's earned his way, really, on special teams," defensive coordinator Jack Del Rio said. "That is the main way he made this team, it's the main way gotten on the field. We're finding ways to do things with him in practice, and he does it well in practice. Then it just adds to the confidence, so when you get to games, you're not afraid to put him in."

Nelson is a big beneficiary of Del Rio's philosophy of keeping backups engaged by using them in sub packages on Sundays. "And if they do well, we build that role," Del Rio said. "So we had that in mind with him and it happened to coincide with Danny going down, so it worked out pretty well."

Brandon Marshall, who started the first three games while Trevathan was out with his first leg injury, slid over and Nelson joined Marshall in the nickel package.

"It was kind of nerve-wracking at first," Nelson said. "But once you play a couple of snaps and get those jitters out, then it's just ball."

Nelson's workload last week included 36 snaps from scrimmage to go with 26 on special teams.

"Man, Corey was huge this game," cornerback Chris Harris Jr. said. "He stepped up and played a great game. Nobody knew we were going to have to use him this much this year or in that game."

Nelson is that rare pro football player who wasn't a big fan of the NFL as a kid. He was into music and academics and was even class president back in high school.

"I didn't really watch football or basketball that much," Nelson said. "I was just into other stuff."

He's still a bit star struck in Denver.

"You meet guys like DeMarcus Ware, Peyton Manning, Wes Welker, Danny Trevathan. Those guys are great players in the NFL and to be taken under their wing is a wonderful experience," Nelson said. "It's something that you have to take advantage of and that you have to cherish."

Notes: LB Lamin Barrow was fined $8,268 for throwing a punch against the Jets. ... OL Paul Cornick has played 31 snaps over the last two games as a second tight end. It's the same role RT Chris Clark played before cracking the starting five. Cornick appears primed to make a similar jump if the Broncos decide to make a change in their O-line in light of all the troubles they've had running the ball and sustaining drives.

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Follow AP Pro Football Writer Arnie Melendrez Stapleton on Twitter: http://twitter.com/arniestapleton