LAS VEGAS — Eddie Alvarez persevered through financial troubles, promotional disputes and a loss in his UFC debut to get back to the cage with a title shot.

And then he beat Rafael Dos Anjos with a fire that's been growing for years.

Alvarez won the UFC lightweight belt Thursday night, stopping Dos Anjos in the first round with a blistering series of strikes.

Alvarez (28-4) needed just 3:49 to finish Dos Anjos (24-8), the Brazilian champion with a five-fight winning streak. The Philadelphia-based contender initially caught Dos Anjos with a damaging right hand, but had to unload dozens of strikes on the still-standing Dos Anjos until finally getting a stoppage.

Eddie is no Rocky-style underdog, but he'll get his fight-crazed city's attention with a moment that validated his lengthy quest.

"This has always been a marathon for me, not a sprint," Alvarez said. "Everybody was always telling me what I should do and when I should do it. I just think if you work hard enough and you love something, these belts are just byproducts of it. This (belt) will not be here forever, but I just think working hard and doing something you're passionate about is important."

Alvarez won the title in just his fourth fight with the UFC, which signed him in 2014 after his protracted departure from the Bellator promotion. The accompanying legal troubles drained Alvarez's bank account and nearly soured him on the sport.

After finally getting to the UFC, Alvarez was trounced by Donald "Cowboy" Cerrone in his first bout. He recovered with split-decision wins over Gilbert Melendez and Pettis to get a title shot — and he was nearly perfect.

Alvarez believed he could better Dos Anjos' formidable striking skills, and he was devastatingly correct: His big right hand appeared to roll Dos Anjos' eyes back in his head.

"I just remember thinking, 'Step on the gas and don't let this get out of the first, because I could be dealing with a long night,'" Alvarez said. "I had him hurt, so I had to empty the gas tank. I told you, don't bring the dog out of me."

Dos Anjos somehow kept his feet against several flurries of big punches, but Alvarez chased Dos Anjos across the cage and unloaded with another bunch of unblocked shots, forcing the referee to stop the bout.

"No excuses. All the credit is for Eddie," Dos Anjos said. "I was with my hands up when I got caught. I saw the punch. I was watching. That's the fight game, man."

Dos Anjos defended his belt impressively with a 66-second TKO of Cerrone in December for his first title defence, but he missed out on a lucrative bout with Conor McGregor in March after breaking his foot in training.

The 12-fight event at the MGM Grand Garden Arena kicked off International Fight Week for the UFC, which is staging shows on three consecutive nights, culminating in UFC 200 on Saturday.

Before the main event, heavyweight contender Derrick Lewis won a split decision over veteran Roy Nelson, and welterweight contender Alan Jouban claimed a brutal decision over iron-chinned UFC newcomer Belal Muhammad.

Lewis (16-4) and Nelson (22-13) traded big shots and fought through several slow periods. Nelson developed a gruesome welt on his ample belly after absorbing a knee strike from Lewis in the first round, and Lewis appeared to dislodge a tooth from Nelson's mouth with a devastating right hand in the final seconds.

Jouban (14-4) earned his fourth win in five fights with a punishing performance against Muhammad (9-1), who was still impressive in his UFC debut. Jouban floored Muhammad repeatedly with kicks and punches, but Muhammad hung on and even dominated the third round.