LAS VEGAS — Floyd Mayweather Jr. went out just as expected — on top and leaving boxing fans yearning for more.

Andre Berto wasn’t expected to give him much trouble, and he didn’t. Mayweather served notice in the opening minute of his fight with Berto that it would be an easy night and it was, with Mayweather winning all 12 rounds on one ringside scorecard.

Another yawner of a win. Another $32 million.

Now he heads into retirement, or so he says.

“You gotta know when to go. I’ve had a great career,” Mayweather said. “I’m leaving with all my faculties. I feel like I’m smart and sharp.”