BROOMFIELD, Colo. (AP) -- Ruslan Provodnikov wore down Mike Alvarado all night with blow after powerful blow until Alvarado couldn't answer the bell to start the 11th round.
The Russian bruiser nicknamed the ''Siberian Rocky'' stunned Alvarado to capture the junior welterweight title Saturday.
Provodnikov (23-2) knocked down Alvarado (34-2) twice in the eighth round with a series of punches near the ropes and finished him off late in the 10th. The fight was halted by referee Tony Weeks, who asked Alvarado a few times if he wanted to continue and Alvarado responded that he didn't.
Promoter Bob Arum, who represents Alvarado, said his boxer might have suffered a concussion.
Provodnikov didn't have trainer Freddie Roach in his corner. Roach remained in the Philippines to work out with Manny Pacquiao, who fights Brandon Rios next month in Macau.
''My team told me, 'You're ready, come out and become a champion,''' Provodnikov said through a translator.
Provodnikov served as chief sparring partner of Pacquiao in his fights against Timothy Bradley and Juan Manuel Marquez.
Not even chants from the home crowd could lift Alvarado, who grew up in Denver and was wearing blue-and-orange trunks in honor of the Denver Broncos. Alvarado got lured into Provodnikov's kind of fight - more brawling than boxing - and never recovered. This was quite a contrast to Alvarado's win over Rios seven months ago, when he had a near flawless fight.
''It just wasn't Mike's night. He was too defensive,'' said Shann Vilhauer, the trainer for Alvarado. ''I think he just started reading all these clips after the (Brandon) Rios fight, that he was a great boxer and he got away from what he's best at. This guy (Provodnikov) was tailor made for him. He didn't take advantage.''
After the fight, Alvarado said that Provodnikov threw the hardest punches he has ever encountered. He also said manager Henry Delgado stopped the fight and that he agreed with the decision.
''It was not worth taking more punishment because the damage could be permanent,'' Alvarado said. ''It just wasn't my night. I have a lot of heart. I'm not a quitter.''
This was the biggest bout in the area since former World Boxing Council lightweight champion Stevie Johnston fell to Jose Luis Castillo in 2000. It also was the first time HBO has televised a live fight from Colorado. Provodnikov didn't pay any attention to the pre-fight ''boos,'' or the crowd constantly chanting, ''3-0-3,'' the city's area code.
''If you want to be a world champion, you have to risk it - go and fight the best, go to his hometown,'' Provodnikov said.
With the win, Provodnikov could likely be in line for the winner of Pacquiao and Rios. The other likely candidate is Timothy Bradley Jr., a fighter Provodnikov lost to in a memorable bout last March.
A rematch with Alvarado isn't out of the question, either.
''Unbelievable,'' said Arthurt Pelullo, the president of Banner Promotions which represents Provodnikov. ''He had a great game plane. Even though Freddie wasn't here, he stuck to the game plan. Alvarado is a tough son of a gun. He was the kind of kid you've got to give respect to. He's a champion.''
On the undercard, Juan Diaz (38-4) landed jab after jab on Juan Santiago (14-11-1), but couldn't put him away in a lightweight fight. Diaz's dominating performance led to a unanimous decision as he remained unblemished in his third fight back after a two-year layoff.
Diaz, a former titleholder nicknamed ''Baby Bull,'' got burned out on boxing and took some time off, even opening a trucking company in Houston.
''I got some much-needed rounds,'' said Diaz, who's hoping for another title shot down the road. ''I think I broke him down very well throughout the fight. ... He gave me a good fight.''