Conor McGregor knocked out Eddie Alvarez in the second round to win the UFC lightweight title and become the first two-class champion in the promotion’s history.

McGregor dominated from the opening bell of the main event of UFC 205 at Madison Square Garden on Saturday night and the sold-out crowd roaring with each blow. McGregor is now the reigning featherweight and lightweight champ.

UFC has not decided if McGregor will be allowed to defend both championships. UFC President Dana White said McGregor could be about the only fighter in the promotion to handle that kind of fight load.