Irishman Conor McGregor made history by becoming the first fighter to hold two UFC belts simultaneously with a second-round knockout of Eddie Alvarez at New York's Madison Square Garden.

The 28-year-old challenger, who went into the fight as the reigning featherweight champion, added the lightweight title when referee John McCarthy stopped the bout with just under two minutes of the second round remaining.

McGregor dominated from the off and had Alvarez on the floor of the Octagon three times in the opening round, with the American wriggling free on both occasions.

The Irishman, with a five-inch reach advantage over his opponent, began showboating in the second, holding his hands behind his back as Alvarez, 32, looked to respond.