When somebody is on your back its hard to know what is going on, not like it was a piledriver.
I'm pretty certain he knew Melvin had his facing downwards considering the position of the legs. The spike was intentional imo.
Lyoto Machida, former UFC LHW hamp
Future UFC MW Champ
Benavidez, Barao, Aldo, Nate, Nick, Lyoto, TBD, JDS
Forever hanging in Anderson Silva nuts