LAS VEGAS — With a destructive barrage of power punches in the waning minutes of a difficult fight, Canelo Álvarez added another achievement to his overflowing list of boxing accomplishments.

The Mexican super middleweight champion is undisputed.

Álvarez became the first four-belt world champion at 168 pounds in boxing history Saturday night, stopping Caleb Plant in the 11th with two dramatic knockdowns.

Álvarez (57-1-2, 39 KOs) added Plant’s IBF title to his own WBC, WBA and WBO belts with a steady tactical performance culminating in a display of his vaunted power to finish the previously unbeaten Plant at the MGM Grand Garden Arena.

Canelo is the most well-known fighter in the world, regardless his weight class. Now he holds the entire weight class. He was the sixth man to win a four-belt title, and he is now joined by Josh Taylor, junior welterweight, as the undisputed champion of their weight class.

“I’m proud to be one of the six,” Álvarez said through a translator before dedicating the win to his Mexican fans.

After stopping three of his previous four opponents, Álvarez had to grind through a challenging matchup with the tenacious Plant (21-1), who usually moved backward and worked behind his jab to stay away from Canelo’s power.

Álvarez remained persistent and racked up a volume of quality punches — and in the opening seconds of the 11th, he sent Plant crashing to the canvas with a vicious combination followed by an uppercut while Plant tried to duck away.

Plant got up unsteadily, and Álvarez dropped him again with two big right hands, forcing referee Russell Mora to end it at 1:05 of the 11th round.

Plant is a strong champion and an inspiring athlete who overcame many personal tragedies to get a shot at Canelo, but the native of Tennessee discovered just how large the gap between Canelo’s contemporaries and Plant.

Álvarez landed more than 32% of his 361 punches, while Plant connected on just 23% of his 441 shots, which included 232 jabs — more than twice as many as Canelo. Álvarez excelled in power punches, landing 40% of 251 power shots while wearing down Plant.

Álvarez is the first Mexican fighter to reign undisputed atop a division, and every flag-waving fan in the vehemently pro-Canelo sellout crowd of 16,586 seemed aware of the achievement. Guadalajara native Alvarez spoke repeatedly before the fight, emphasizing his determination to achieve the feat for Mexico as well as himself.

Álvarez extended the most successful active career in boxing with his eighth consecutive victory in just over three years. He hasn’t lost in 16 fights since dropping a majority decision to Floyd Mayweather in 2013, with only a draw against Gennady Golovkin blemishing his record.

Álvarez and Plant had no personal animus until September, when Álvarez took offense to an insult from Plant during a news conference in Beverly Hills to promote the bout. Álvarez and Plant briefly scrapped, leaving Plant with a cut on his face and a new avenue of motivation.

Plant opened the biggest bout of his career with a solid game plan, tapping Álvarez with a solid jab and moving away from his opponent’s superior power, frequently using a shoulder roll to avoid trouble. Álvarez steadily walked down Plant and did damage in the fourth, backing him against the ropes and letting combinations fly.

Álvarez showed little fear of Plant’s punches, and he got even less heedful as the bout progressed. Álvarez gradually landed more effectively in the middle rounds, moving Plant backward and even daring the cautious Plant to hit him in the seventh.

Boxing has been subject to deserved criticism for being a venue for promoter rivalries and fractious sanctioning agencies that keep the best fighters from meeting up too often. But Álvarez used his star power to join an elite club by winning all four major belts.

Only five men had ever achieved four-belt undisputed champion status since the feat became possible with the WBO’s advent: middleweights Bernard Hopkins and Jermain Taylor, junior welterweights Terence Crawford and Taylor, and cruiserweight Oleksandr Usyk.

Taylor won the feat against Jose Ramirez in May. His first simultaneous defense of all four belts against Jack Catterall is scheduled for February in Glasgow.

Super middleweight veteran Anthony Dirrell won his first win in almost three years with a stoppage of Marcos Hernandez in the fourth round. He did this by using a vicious uppercut. Dirrell, 37, celebrated by doing a standing backflip.