LAS VEGAS -- Amir Khan vowed to be impressive in his first welterweight fight, and he was.
Khan knocked Luis Collazo down three times Saturday night on his way to a lopsided decision win he needed desperately if he hopes to fight Floyd Mayweather Jr. In his first fight in more than a year, Khan dominated against a former champion while looking sharp at his new weight.
Khan lost out to Marcos Maidana to fight Mayweather, but made the best out of his spot at the top of the undercard for the Mayweather-Maidana card by beating and bloodying Collazo.
"People want to see that fight between me and Floyd," Khan said.
Khan, who said he was starving himself to make 140 pounds, was cautious with Collazo, but used his hand speed from the outside to land right hands to the head from the first round on. He dropped Collazo with a right hand in the fourth round, then dropped him twice in the 10th round.
Collazo finished the fight, but he was bleeding from a cut by his right eye and his face was swollen from Khan's right hand. Two judges scored it 119-104, while the third had it 117-106.
Khan's dominance was shown in punch stats that showed him landing 264 of 692 to 140 of 511 for Collazo.
"I had to hang in there," Collazo said. "You have to take me out, that's what it's all about."
Khan, who improved to 29-3, thought he was going to be fighting Mayweather instead of Maidana. He gave up a title fight in December to wait for Mayweather, but didn't get picked for the fight despite winning an online poll conducted by Mayweather.
"It was very hard because Collazo is really awkward," Khan said.
In another fight, Adrien Broner came back from his only professional loss to win a lopsided decision over Carlos Molina in a 140-pound bout.
Broner was simply too fast for Molina, who pressed the action but was consistently beaten to the punch. Broner never seemed to hurt Molina, but won all 10 rounds on one scorecard and won easily on the other two.
"As you can see I didn't have any trouble," Broner said. "It was sparring on national television."
Broner was fighting for the first time since being beaten by Maidana in a December fight, when he was knocked down twice and lost a decision. That fight was at 147 pounds, but Broner moved back down to 140 to fight Molina.
Broner (28-1, 22 knockouts) said he felt better at the lower weight after briefly holding a piece of the welterweight title. Ringside punch stats showed him landing 237 of 614 punches to 150 of 550 for Molina.
"This is definitely the ring weight," he said. "I'll fight anybody, but I want to fight (Manny) Pacquiao before he leaves."
In another bout, J'Leon Love came back from a fifth round knockout to beat Marco Antonio Periban in a 168-pound fight.
Love won a 10-round decision on all three ringside scorecards to remain unbeaten in 19 fights. Periban fell to 20-2-1.