By Keith Idec

LAS VEGAS – As popular as Gennady Golovkin has become among Mexican boxing fans, he undoubtedly entered enemy territory Friday afternoon.

Golovkin was booed by a loud, proud, pro-Canelo Alvarez crowd of over 10,000, which packed MGM Grand Garden Arena for their official weigh-in. The atmosphere was wild a day before one of the two biggest fights in the United States this year.

Kazakhstan’s Golovkin weighed in at 160 pounds, right at the middleweight limit. Mexico’s Alvarez also weighed in at 160 pounds for their 12-round middleweight title fight Saturday night at nearby T-Mobile Arena. 

Alvarez weighed four pounds less than the career-high 164 pounds he weighed for his last fight. That 12-round victory over Mexican rival Julio Cesar Chavez Jr. was contested at a catch weight of 164 pounds May 6 at T-Mobile Arena.

Golovkin (37-0, 33 KOs) will defend his IBF, IBO, WBA and WBC middleweight titles against Alvarez (49-1-1, 34 KOs). Alvarez refuses to fight for the WBC title because he feels the Mexico City-based sanctioning organization forced him to give up its middleweight title in May 2016 by imposing a deadline for him to agree to fight Golovkin.

Alvarez still owns The Ring magazine’s middleweight title and is considered boxing’s lineal middleweight champion because no one has beaten him since he soundly defeated Miguel Cotto for the WBC, Ring and lineal middleweight titles in November 2015.

Golovkin, 35, and Alvarez, 27, won’t have to weigh in again unless they want to step on HBO’s unofficial scale Saturday night.

The IBF adjusted its second-day weigh-in rule last month because of what happened the day of Golovkin’s last fight, a 12-round, unanimous-decision victory over former WBA middleweight champion Daniel Jacobs (32-2, 29 KOs). Jacobs skipped the second-day weigh-in without notifying Golovkin’s handlers, but Golovkin adhered to the IBF’s rule and didn’t add more than 10 pounds over the middleweight limit of 160 by the morning of their fight (https://www.boxingscene.com/sanchez-jacobs-weighed-182-canelos-weight-affect-ggg--120479).

Abel Sanchez, Golovkin’s trainer, expects Alvarez to weigh at least 175 pounds when their fight starts Saturday night. Sanchez said Golovkin won’t weigh more than 171 pounds.

Alvarez’s trainers, Eddy and “Chepo” Reynoso, have said Alvarez will add only “seven or eight” pounds between the weigh-in and the fight.

Below are the weights for the first three fights HBO Pay-Per-View will televise Saturday night (8 p.m. ET/ 5 p.m. PT; $79.99 in HD):

Joseph Diaz (24-0, 13 KOs), Downey, California, 126 pounds, vs. Rafael Rivera (25-0-2, 16 KOs), Tijuana, Mexico, 127 pounds, 12 rounds, WBC featherweight elimination match.

Randy Caballero (24-0, 14 KOs), Coachella, California, 121 pounds, vs. Diego De La Hoya (19-0, 9 KOs), Mexicali, Mexico, 122 pounds, 10 rounds for the NABF super bantamweight championship.

Ryan Martin (19-0, 11 KOs), Cleveland, 135 pounds, vs. Francisco Rojo (20-2, 13 KOs), Mexico City, 135½ pounds, 10 rounds for the WBA Intercontinental and WBC Continental Americas lightweight titles.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.