Amir Khan looks sharp -- maybe too sharp -- against Devon Alexander

On this night, the nickname was almost as right as the boxer who carries it.

Welterweight Amir (King) Khan took the main event in the MGM Grand Garden on Saturday night, an event labeled “The Royal Battle,” in impressive fashion.

It was not only a unanimous decision, but it easily could have been a wakeup call for Floyd Mayweather Jr.

Speaking of kings — and that’s what Mayweather currently is in a fight game that ranks him pound-for-pound best — this fight might have been the perfect audition for his next opponent.

Perhaps, in a couple of ways.

Knowing how protective Mayweather is of his unblemished 47-0 record, this could provide him food for thought.

Khan, in his dominating performance over a former champion, Devon Alexander, was scary good.

“It’s the best Amir Khan I have ever seen,” said his promoter and former boxing superstar Oscar De La Hoya. “I sure wouldn’t fight him.”

De La Hoya, who fought everybody in his career, called Khan’s performance “almost a perfect fight,” and said that, after what everybody saw Saturday night, it might have Mayweather “thinking twice” about taking on Khan.

Mayweather, who would be almost 10 years senior to the 28-year-old Khan when and if they fight, has two more lucrative fights left on his contract with Showtime.

Strangely, this one could end up sending Mayweather closer to a fight with Manny Pacquiao. That’s the fight that has never happened and has generated years of frustrating waiting for fight fans.

“I didn’t call Mayweather out with total confidence before,” Khan said afterward. “Now, I’m ready. I’m at my peak.”

Khan’s dominance was not lost on the judges. Jerry Roth had it 120-108, a shutout of Alexander. Glenn Feldman gave Alexander one round for 119-109 and John McKaie gave him two for 118-110.

Khan (30-3) scored repeatedly with lunging jabs and lightning combinations.

A somewhat befuddled Alexander said afterward, “I know I could have done more, but I was just having a hard time catching him. This wasn’t the way I wanted it to go. I tried to follow the game plan, but I just couldn’t do it.”

Alexander had his own dreams of getting a Mayweather match, but those were put on hold, or maybe eliminated, by the boxing package Khan sent at him.

“It was a disappointment,” Alexander said.

Khan, from Bolton, England, has been an up-and-down fighter. There have been hints at this spectacular side, but then there have been defeats.

He is now trained by Virgil Hunter, who is best known for taking Andre Ward to the top of his division.

Hunter said he was impressed with Khan’s show and Khan gave him credit for the work he has done to improve his jab.

“I think I have the best jab in the business now,” Khan said.

Against Alexander, a left-hander who had said before the match that Khan would not be able to handle him because he hadn’t faced “a slick southpaw before,” Khan followed a powerful jab with four-, five- and six-punch combinations.

For Alexander, who entered the night with a 26-2 record, it had to feel like a constant swarm of birds, dive-bombing him. Big birds.

“I think I’ve proved myself at 147 pounds,” Khan said.

The only question now is whether he proved himself for Mayweather, or scared him away. Only time, and the complicated politics and egos of boxing will tell.

In the undercard at the MGM, fast-rising Keith Thurman, also a welterweight, acquitted himself well as a versatile boxer — despite being booed by some of the fans in the crowd of 7,768 for his apparent inability to draw blood — by winning a unanimous decision. He beat previously unbeaten Italian veteran Leonard Bundu, 120-107 on all three cards.

His hand speed and footwork were similar to Khan’s, just not as impressive.

In another undercard fight, veteran Abner Mares extended his record to 28-1-1 by winning a brutal brawl against fellow Mexican Jose Ramirez. Ramirez went down three times and his corner called it off after the fifth round.

Also, former champion Victor Ortiz made his comeback a success, knocking out Manuel Perez of Denver with a huge left hook in the third round.

bill.dwyre@latimes.com.

Twitter: @DwyreLATimes.