LAS VEGAS - Oscar De La Hoya went into the ring Saturday night knowing he might only be a few minutes away from the end of his lucrative career.

He left as a champion who might want to rethink his retirement plans after turning in his most impressive performance in years.

Fighting for the first time in 20 months, the Golden Boy dominated Ricardo Mayorga, knocking down the Nicaraguan brawler in the first round before finally stopping him in the sixth to claim the WBC’s 154-pound title.

Showing no signs of rust or reluctance, the 33-year-old De La Hoya flattened Mayorga in the opening minute and never let up, unleashing waves of punishing head shots until Mayorga went down for the third time at 1:25 of the sixth. De La Hoya then jumped onto the ropes with the flair of a champ who was back in his element once again.

“No matter what, I was going to stand up to him, let him know right away that I was here to fight,” De La Hoya said. “I had to show the bully that I wasn’t going to back down. He fought recklessly, but I stood my ground, and he saw I wouldn’t back down.”

From the opening shots to the fantastic final flurry, it was the best fight for De La Hoya since he stopped Fernando Vargas four years ago, and a near-perfect result in what De La Hoya claims will be his penultimate fight.

De La Hoya has said he wants to finish his career Sept. 16 — and after this performance, there’s a genuine chance of a tantalizing bout with Floyd Mayweather Jr., the world’s top pound-for-pound fighter whose father trains De La Hoya.

Mayweather watched De La Hoya’s dominance from ringside, then said he wants the September fight, calling it “the biggest fight in boxing history.”

“If Oscar wants to go out on top being the best, I believe on Sept. 16 we must meet,” Mayweather said. “It’s about legacy.”

But Floyd Mayweather Sr., who devised De La Hoya’s precise plan to stop Mayorga, doesn’t think he could stomach such a fight — and De La Hoya, who said there’s still “a good chance” he might retire, won’t take the bout without his trainer.

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“I don’t feel good about that at all,” Mayweather Sr. said. “What kind of father am I if I let my son get knocked out? I’m not saying my son can’t win the fight, because he can ... but if I’ve got anything to do with it, and I have a lot to do with it, it ain’t going to happen.”

De La Hoya (38-4, 30 KOs) clearly hadn’t lost his passion for the ring since Bernard Hopkins stopped him in the ninth round with a devastating body punch in September 2004. Spurred by Mayorga’s pre-fight insults toward his family and courage, he overwhelmed the wild-punching Mayorga with clinical right hands and a handful of devastating left hooks, stalking him around the ring and controlling nearly every moment of the fight.

He sent Mayorga to the canvas just 60 seconds in, artfully ducking a wild punch and responding with a strong right and a brutal left hook. The crowd stood, and De La Hoya cast a disdainful glance over his shoulder as he walked to the neutral corner.

The fight got no better for Mayorga (27-6-1), with De La Hoya’s tactical precision — using his right hand with uncommon grace — and surprising power taking a quick toll.

De La Hoya knocked him down again in the sixth, when a glassy-eyed Mayorga stayed momentarily on his wobbly feet before finally going down for good. De La Hoya also went to the canvas when referee Jay Nady pushed him away from his fallen opponent, but he sprung up to climb the ropes in triumph.