Conor McGregor won his fourth straight UFC fight Saturday night in Las Vegas but it wasn't without controversy. The brash Irishman moved ahead in the featherweight rankings with a first round TKO win over Dustin Poirier at UFC 178, but the unfortunate manner in which it ended still left plenty of questions regarding not just the fight but the rising star's ability to take on and possibly take out the very best in the world.

After a good number of striking combinations thrown from both men, with mostly only glancing connections for either, McGregor caught a ducking Poirier with a left hook to the back of the head. The American appeared to go out and fell to the mat.

McGregor followed up with strikes to the downed Poirier, forcing referee Herb Dean to step in and call a stop to the fight. Strictly speaking, strikes to the back of the head area that McGregor hit Poirier on are not allowed in unified MMA rules.

However, Dean either didn't notice the placement of the quick shot or, decided no foul could be called because McGregor's punch seemed to be aimed and thrown at a legal area of Poirier before the Louisiana fighter ducked into it. In either case, McGregor moves on in the 145 pound class with this high-profile, though controversial win, and was quick to call for a title shot in his post-fight interview with Joe Rogan.

"What the other featherweights don't understand, is that it's a whole ‘nother game when they get hit by me," McGregor told interviewer Joe Rogan.

"The world title is next."

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