Julio Cesar Chavez Jr. makes weight and makes his case: He’s serious about beating Canelo Alvarez

Julio Cesar Chavez Jr. on Friday answered those who’ve insisted that his extended indifference toward boxing meant he’d checked out of the sport.

The son of the legendary Mexican fight warrior exhorted a packed crowd at MGM Grand by stepping on the stage and raising his arms in triumph after weighing in at 164 pounds, a half-pound under the catch-weight limit for his Saturday showdown against countryman Canelo Alvarez.

“I feel good and I’m ready for a fight that would go 12 hard rounds, and if the knockout comes, I’m ready. I’m very happy to be a boxer,” Chavez, 31, told The Times after stepping off the stage where his father, a former three-division champion, enthusiastically shook his arms forward, flashing a beaming smile at a festive Cinco de Mayo crowd of supporters.

Alvarez (48-1-1, 34 KOs) also weighed 164 pounds.

Former middleweight champion Chavez (50-2-1, 32 knockouts) hasn’t weighed that low since 2012, and subsequent trips to the scale have been turbulent events in which last-minute catch-weight deals were struck to keep him on cards.

The repercussions of any repeat laziness were steep : a $1-million penalty if he weighed one-tenth of a pound over the contractually stipulated 164.5 pounds for Alvarez.

Chavez said making weight should serve as the leading indicator of his preparedness for this career-defining bout.

His camp showed an early Friday morning video in which Chavez was said to have shed the final ounces while shadow boxing. He said the steady weight cut supervised in the mountains above Mexico City by conditioning coach Angel “Memo” Heredia will aid his fight-night energy.

Chavez’s sparring partner, Saturday night co-main-event fighter Marcos Reyes, said, “This camp, he took serious. He looks good. He’s doing what he needs to do to win.”

“It was very important,” Chavez said. “I felt no sacrifice to my body to make weight. That would’ve affected my condition by the time of the fight.”

He immediately sipped an energy drink after weighing in wearing white boxer-briefs and said he expects to rehydrate to around 185 pounds when he steps in the ring.

Since Alvarez’s last fight was at 154 pounds, Chavez’s size advantage will be his best weapon as he’ll seek to bully and fatigue the favored Alvarez, while throwing heavier punches at the faster, more skilled and disciplined former two-division champion.

“If he uses all of his physical size, that’s the idea — bang away, bang away, it’s like chopping a tree down. Chop on that thing long enough, it’s going to fall,” said Chavez’s assistant manager, Sean Gibbons.

“Yes, that is my strategy,” Chavez said. “I can do it with the extra weight I’ll have. … I love the way I feel. I’m light, I’m faster. … I had to make sure that I was at top shape to win.”

Alvarez, meanwhile, supplied his own dramatic touch by standing alongside Chavez, flashing an expression of menace and whipping a vicious left-handed punch to the air as cameras snapped. Alvarez seeks to be “light and fast,” his promoter Eric Gomez said, and expects to be around 175 pounds at the time of the fight.

“I’m very excited and very happy and I want to tell all the fans, tomorrow is for you,” Alvarez said. “I’m very happy that [Chavez] made weight because that’s proof that he worked hard and trained hard and that’s a guarantee we can give the fans a great fight that they deserve.”

An Alvarez victory would position him for a September super-fight against unbeaten three-belt middleweight champion Gennady Golovkin, who might attend Saturday’s bout.

“If Canelo looks really good, there’s a good chance the fight happens,” Golovkin’s promoter Tom Loeffler said.

The raucous atmosphere on the celebratory holiday enlivened the fighters as fans took turns roaring for their favorite inside the arena, then again as they exited in herds. The bout will be at 20,000-capacity T-Mobile Arena, less than a mile from MGM Grand.

“Everyone is supporting both fighters,” Spanish-language television/radio personality Piolin said. “We’ve never felt this fever that is here right now. We’re going to have an amazing event.”

lance.pugmire@latimes.com

Twitter: @latimespugmire