Conor McGregor knocked out Chad Mendes at 4:57 of the second round to claim the interim UFC featherweight championship Saturday night at UFC 189 at the MGM Grand Garden Arena.
After being lengthily forced to defend himself from his back, McGregor caught Mendes with straight left hands and a kick to the body.
As Mendes toppled over near the fence, McGregor pursued his weakened opponent and rained him with wicked lefts that prompted referee Herb Dean to stop the fight.
While there were less than three seconds left in the round when the fight was stopped, Mendes didn't protest.
In fact, Mendes admitted he has no idea what was happening at that time.
He did remember getting back to his feet, which he admitted was a mistake since it allowed McGregor to tee off on him.
To his credit, Mendes (17-3) was able to take McGregor down in each round and opened a cut over his right eye in the first.
Mendes, 30, took a 10-9 lead on the scorecards after the first round.
McGregor has now won all of his six fights in UFC and has knocked out all his past four opponents.
McGregor said he was able to disprove talks that he was a protected fighter and was gifted a title shot.
The 26-year-old McGregor (18-2) was supposed to challenge defending champion Jose Aldo for the regular title.
That forced McGregor to switch his fighting style from a lanky standup fighter in Aldo to a short, compact wrestler in Mendes.
However, Aldo (25-1) suffered a broken rib and had to withdrew June 30, but McGregor said he was being avoided.
McGregor noted that he had bigger injuries but showed up in his fights and performed well.
The 28-year-old Aldo, who is expected to return this year, is also undefeated in UFC and is ranked No. 2 pound-for-pound fighter in the world.
UFC president Dana White said a title unification bout between McGregor and Aldo will likely be held in Las Vegas.