Saul ‘Canelo’ Alvarez digs deep while training for Miguel Cotto

The comforts of life Saul “Canelo” Alvarez has earned by emerging as Mexico’s most popular fighter are outside his gym.

Time will come for leisure inside his San Diego home, for the thrill ride in his luxury cars.

For now, less than a month before Alvarez’s anticipated showdown against middleweight world champion Miguel Cotto at Mandalay Bay in Las Vegas on Nov. 21, the only thing “Canelo” needs is a towel.

As his trainer Eddy Reynoso rolls out a body-length foam mat, Alvarez dips his hand deeply into a duffel bag and expresses delight. He’s found the exact plain-white towel he needs.

The glamour of his ring walk, the roar at his introduction seem so far away now from this quiet, where a single boxer endures the agony of fight preparation.

Alvarez, with only his two trainers, a publicist, a physician and a promotional employee in the warm gym, sets the towel on the foam mat and begins an exhausting routine of sit-ups. Over and over — until the shirtless Alvarez and his towel are soaked in sweat.

The 25-year-old fighter (45-1-1, 32 knockouts) knows his power punching will be an advantage over Cotto, who turns 35 on Thursday.

What he’s working on in camp is maximizing his speed and fitness, incorporating drills such as rapid jerks forward and upward with a weightlifting bar, punching small sections of swimming pool flotation tubes with straight rights and uppercuts and repeatedly throwing a mini-medicine ball against a wall.

“This fight is my opportunity to show the world why I think I’m a champion,” Alvarez said in Spanish through an interpreter.

Thursday marks the 10^th anniversary of Alvarez’s first pro bout, a fourth-round technical knockout of Abraham Gonzalez in Jalisco, Mexico.

An eight-fight knockout streak started the next year, and Alvarez knocked out 11 of 12 opponents through 2010, a stretch that counted Cotto’s brother, Jose Miguel, and former welterweight world champion Carlos Baldomir among the fallen.

Most recently, on May 9, Alvarez took out James Kirkland in the third round.

But the disciplined, four-division champion Miguel Cotto, counseled by famed cornerman Freddie Roach, will work to avoid the heavy hands and outsmart the younger Alvarez, as Floyd Mayweather Jr. so obviously did in their 2013 pay-per-view bout that generated 2.2 million buys.

“He has power, now he needs to explode,” Reynoso said of Alvarez during the training session observed by The Times last week.

It irks the Alvarez camp that Mayweather and to a lesser extent Cuban Erislandy Lara’s split-decision loss to Alvarez are seen as proof of how the former light-middleweight world champion has been exposed.

Beating Cotto would quiet the skepticism.

“When Julio Cesar Chavez Sr. was 89-0 and lost to Frankie Randall, people criticized [Chavez] for not being able to move in the ring, that he couldn’t block or play defense,” Reynoso said. “How can he be no good when his record speaks for itself?”

Alvarez says he’s hopeful the fight allows him to display his newly enhanced skills.

“I’ve learned from every single fight, every single opponent — some great fighters,” Alvarez said. “I’ve corrected the errors. I’m going to go in there and do what I need to do.

“We’ve been training very hard to ... apply everything I’ve learned to the ring, to be successful that night. I love to push myself. I take the time to look at my videos after a fight to see not what I did right, but what I did wrong, to learn from those mistakes.”

Grinding through the everyday workout chore of sit-ups will help get him there, Alvarez assessed.

He strives to be prepared to display “everything. Speed, power, agility, stamina, intelligence — everything I need to apply on that fight night. I can’t leave anything out.

“I’m very conscious of Miguel Cotto’s career … I need to do my part on that night to have victory and create my own legacy in this sport of boxing.”