CHARLOTTE, N.C. -- The Carolina Panthers held a private workout for Nebraska defensive end/outside linebacker Randy Gregory on Monday, according to ESPN's Josina Anderson.

You may be wondering why.

Gregory is projected to be selected in the top 10 of the upcoming draft. ESPN's Todd McShay has him going to the New York Jets at No. 6 in his most recent mock draft . Carolina has the 25th pick and doesn't have a history under general manager Dave Gettleman of trading up in the first round.

Gregory failed a drug test for marijuana at the NFL combine and reportedly had two positive tests for marijuana at Nebraska. Carolina recently washed its hands of defensive end Greg Hardy, who is still on the commissioner's exempt list as the league decides how to handle his domestic violence case.

So why are the Panthers spending time working out Gregory?

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Gregory is an elite pass-rusher. The Panthers are looking for an elite pass-rusher to replace Hardy, who led the team with 15 sacks in 2013.

Coach Ron Rivera said last week at the NFL owners meeting that the Panthers have a "combination of guys" who can put up the type of numbers Hardy did.

He said 2014 second-round draft pick Kony Ealy is "very close to taking another step." He also said Ealy isn't there yet.

"We've got a good, solid foundation," Rivera said.

He paused, and then added, "Would we love a double-digit [sack] guy? Absolutely."

Gregory could be that guy. He has an explosive first step coming off the edge that can make opposing offensive coordinators cringe. He can be disruptive as he showed at Nebraska with 17.5 sacks and 25.5 tackles for loss in two seasons.

So the Panthers are doing their due diligence on a player who, because of the failed drug tests, possibly could fall to late in the first round. They've shown recently with defensive end Frank Alexander that a failed drug test isn't enough to toss a player aside.

Alexander missed 14 games last season for failing two drug tests.

If Gregory falls to No. 25 and the Panthers are comfortable with what they've learned through extensive research, he'll be hard to pass up.