Amir Khan set to box Danny Garcia

Amir Khan, who regained one light-welterweight title earlier this week without entering the ring, has a chance Saturday to win another if he can stop unbeaten Danny Garcia.

Lamont Peterson had defeated Khan by a controversial decision in December but then tested positive in May for synthetic testosterone and admitted he started using the substance in November. The World Boxing Assn. this week stripped its title from Peterson and returned it to Khan.

In a way, Khan’s loss to Peterson never happened.

The danger for the British fighter is acting as if it never did.

“Khan didn’t work well enough on the inside,” said Paulie Malignaggi, the current WBA welterweight champion whom Khan defeated by technical knockout in 2010. “His only defense was to put his head down, or push the guy’s head away.”

By pushing Peterson’s head, Khan had two points deducted in the second half of the fight and lost the split decision by one point on two scorecards in Peterson’s hometown of Washington, D.C.

“Definitely, I know I need to be better,” Khan said this week. “We have to stick to the jab. I thought I did that well in the first three rounds, but then I stopped using it, and that’s how he made it a fight. I need to not stay on the ropes too long, not stay in the pocket too long.”

Khan (26-2, 18 knockouts) and Garcia (23-0, 14 KOs) each weighed in at 139 pounds Thursday for the 140-pound fight at Mandalay Bay in Las Vegas.

Peterson’s positive test was announced 10 days before a scheduled May 19 rematch with Khan, forcing the bout’s cancellation and the insertion of World Boxing Council champion Garcia, from Philadelphia.

Garcia is coming off a gritty victory over veteran former world champion Erik Morales in April.

“In the 11th round, when he cut me on my eyebrow and I started bleeding and my nose was a little swollen, I stood there and I traded with a Mexican warrior and the fans loved it,” Garcia said. “When the time got heated, when people thought my nose was broken and my eye was bleeding, my heart could have easily went off. But my heart got pumped up.”

After enduring two training camps, Khan maintains the extra work was an opportunity to strengthen his fighting.

“My speed, my power, my movement will all be big advantages,” Khan said. “I’ve been in there against guys in their prime. Garcia has fought guys like Kendall Holt and Erik Morales who are over the hill.”

Garcia, 24, said such criticism will stop if he defeats Khan.

“If you’re the world champion, who are you supposed to fight? Are you supposed to fight bums and pad your record?” Garcia said on a recent conference call. “You’re supposed to fight the best people in their prime, and that’s what I want to do.

“I want to be the best and . . . I want to build my legacy starting young.”

Khan, 25, said if he wins he believes he will have cleaned out the 140-pound division and will aim next to fight Floyd Mayweather Jr., who’s due to be released from jail by next month. He’s serving time after pleading guilty to domestic battery.

Mayweather’s advisor and manager have been in discussions this week in Las Vegas with Khan’s promoter, Richard Schaefer, about the match idea.

“I met with Mayweather’s manager, and they’re very interested in having a fight,” Khan said. “It’d be brilliant . . . it’d bring fans back to the sport.

“But at the moment, I have to beat Garcia.”

lance.pugmire@latimes.com

twitter.com/latimespugmire