NEW YORK – Roy Nelson clearly has some lingering doubts about whether Mirko Cro Cop will be clean when he enters the cage for their rematch at Bellator 216.

More than seven years after their first meeting at UFC 137 in October 2011, Nelson (23-16 MMA, 1-2 BMMA) will attempt to score another victory over heavyweight legend Cro Cop (37-11-2 MMA, 0-0 BMMA) in a rematch that’s been roughly 11 months in the making.

The fight originally was supposed to happen at Bellator 200 in May, but Cro Cop suffered a knee injury that forced him off the card and required surgery. He’s back now, though, and appears to be in tremendous shape for Saturday’s Bellator 216. That raises an eyebrow for the ever-skeptical “Big Country.”

“Cro Cop is back being on a streak, but I don’t know what that has to do with,” Nelson told MMAjunkie at Bellator 216 media day. “When he pulled out of my fight, he had a fight, he had knee surgery, he had rehab, and he was able to come back in three or four months. I think his docs need to come over here for the NFL and some of these guys that get messed-up knees, they could be back in a week.”

Bellator 216 takes place at Mohegan Sun Arena in Uncasville, Conn. Nelson vs. Cro Cop is part of the DAZN-streamed main card following prelims on MMAjunkie.

MMAjunkie reported this week that all pre-fight drug tests administered by the Mohegan Tribe Department of Athletic Regulations came back clean, including Cro Cop. Nelson claims he was tested again early in fight week, and he said he hopes the same for Cro Cop, and that the results are expedited.

“They pulled me an extra day early just to do a pee test,” Nelson said. “I hope the results come back before the fight, because if it doesn’t come back before the fight, I don’t even know why they did the test. Wasted resources.”

Nelson has valid reason to be concerned about Cro Cop. The veteran heavyweight never served a two-year suspension issued by the U.S. Anti-Doping Agency during his UFC career, and his past 11 fights have taken place in either Japan or Russia, where there are no formal athletic commissions sanctioning the events.

Nevertheless, Nelson’s fight with Cro Cop has fallen apart before, and he said he doesn’t want that to happen again. At 42, Nelson only has so many fights left in him – assuming he does it the right way.

“(I won’t have to retire if) I go to Croatia and get some good doctors,” Nelson said. “It’s more about if you’re competitive. I’m about being competitive. If some guy that shouldn’t beat me up beats me, then I don’t want to do this.”

To hear more from Nelson, watch the video above.

For more on Bellator 216, check out the MMA Rumors section of the site.