LAS VEGAS — The world finally had the two of them contained Saturday night, in a roped-off ring where they had to remain silent and just get on with it. Two mouthy welterweights, neither the best role model for his respective legion of young fans, throwing mocking looks and punches in a spectacle of the inevitable.

Conor McGregor, 29, a Dubliner more famous in some circles than James Joyce, entered the ring first; he is a mixed martial arts champion who was undefeated in professional boxing because he had never fought a round. Following soon after was Floyd Mayweather Jr., 40, easily the best fighter of his generation; he, too, was undefeated, at 49-0.

So, then: Do the math.

This wildly lucrative contrivance posing as a boxing match for the ages ended as expected. With clinical detachment, Mayweather pounded McGregor’s punch-reddened face until the referee granted mercy in the 10th round, declaring a technical knockout and perhaps sparing some measure of the Irishman’s future cognitive abilities.

“I thought it was close,” said McGregor immediately after the fight, to the concurrence of no one.

Mayweather, looking as though he had just returned from a light jog, summed things up with a charitable: “I think we gave the fans what they wanted to see.”