• Unbeaten southpaw Alimkhanuly now has 14 wins with nine knockouts.
• Alvarez is the undisputed super-middleweight champion, while Charlo holds the WBC middleweight belt.
Kazakhstan's Janibek Alimkhanuly defended his WBO middleweight world title with an impressive second-round knockout of Canada's Steven Butler.
The 30-year-old caught Butler with a left hook and followed with a series of lefts, flooring Butler three times before the referee stopped the bout.
Unbeaten southpaw Alimkhanuly now has 14 wins with nine knockouts.
Afterwards he called out Mexico's Saul 'Canelo' Alvarez and American Jermall Charlo.
Alvarez is the undisputed super-middleweight champion, while Charlo holds the WBC middleweight belt.
"Champions and boxing superstars, where are you?" Alimkhanuly said.
"I'm the most avoided fighter. I'm the middleweight king.
"Canelo and Charlo, I'm coming. I'm ready for anybody, any time, anywhere."
On the same card in Stockton, California, Australia's Jason Moloney won his first world title with a majority decision win over Vincent Astrolabio for the vacant WBO bantamweight belt.
The 32-year-old from Melbourne won on two judges' cards, 115-113 and 116-112, while the third had the fight as a draw.
Elsewhere, American Rolando Romero beat Venezuela's Ismael Barroso in Las Vegas in a controversial ninth-round stoppage to win the vacant WBA super lightweight title.
Referee Tony Weeks stopped the bout in the ninth round with Romero swinging but seemingly not landing against Barroso.
"He was a warrior. He wanted to keep going. He should have been able to keep going," Romero said after his win.
His win was his 15th in 16 fights and means he takes the world title on his debut in the division.
Romero was set to meet unbeaten world title holder Alberto Puello but the Dominican returned a positive A-sample for a performance-enhancing substance last month and was made a "champion in recess" on Wednesday.
Floored in the third round, Romero knocked down Barroso at the start of the ninth, although the South American called it a push.
"He [the referee] just stopped the fight. He didn't tell me anything," Barroso said.
"You could see it clearly. I was hitting him. There was nothing he was hitting me with clearly. I don't understand."