Heavyweight Roy Nelson has long been regarded as one of the hardest-hitting fighters on the UFC roster. "Big Country" has amassed 13 knockouts in his professional career, including dramatic finishes of Cheick Kongo, Stefan Struve and Mirko Cro Cop.

But Nelson's most recent win may have been his most devastating.

In April of 2014, the then 38-year-old Las Vegas native walked into the Du Arena in Abu Dhabi with back-to-back losses on his record for the first time since 2011. Nelson was matched up against submission specialist and PRIDE Fighting legend Antonio Rodrigo Nogueira, whose punching power was nothing to sneeze at despite 21 of 34 career wins came by way of submission.

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Nelson hurt Nogueira early, dropping the Brazilian within the first minute with a heavy right hand at the 4:04 mark, and landed another vicious overhand right with 1:55 left in the opening round. "Minotauro" made it back to his feet but Nelson unleashed yet another overhand right 25 seconds later that landed flush and sent a stiffened Nogueira to the canvas.

Check the fight above and let us know if this is Nelson's most devastating knockout.

Nelson returns to the Octagon on Sept. 26 to face former UFC heavyweight champion Josh Barnett at UFC Japan.