Gennady Golovkin and Saul "Canelo" Alvarez were preparing for a middleweight "war" here Saturday as the final countdown to their acrimonious rematch began.

Undefeated Kazakh world champion Golovkin and Mexican idol Alvarez will climb into the ring at Las Vegas's T-Mobile Arena, a year after battling to a controversial draw at the same venue.

Most observers believed Golovkin did enough for victory, but Alvarez was handed a draw after a wild divergence in the judge's scorecards. One judge scored it 115-113 for Golovkin, while another had it 118-110 for Alvarez and a third scored it even.

The 12-round rematch is the most eagerly anticipated fight of 2018 and takes place against a backdrop of mounting animosity between Golovkin and Alvarez.

Tempers threatened to boil over at Friday's weigh-in, where Alvarez appeared to charge at Golovkin before members of the two fighters' entourages intervened.

Golovkin, who could claim a piece of boxing history with a 21st consecutive defence of his titles later Saturday, appeared the more composed at Friday's face-off.

"All I could feel was fear from them," the 36-year-old WBA, WBC, and IBO champion added.

The hard-hitting Golovkin (38-0-1, 34 knockouts) is expected to carry a slight weight advantage into the ring on Saturday. He tipped the scales at 159.6 pounds (72.4 kilos) on Friday, against Alvarez's 159.4lbs.

Alvarez (49-1-2, 34 knockouts), is likely to enjoy the lion's share of support in Saturday's sold-out fight, which takes place on the eve of Mexico's Independence Day celebrations.

An initial rematch scheduled for May 5 was cancelled after Alvarez twice tested positive in February for the banned substance Clenbuterol, which can help with weight loss and muscle-building.

Alvarez, who was later suspended for six months, insisted the drug had entered his system inadvertently through contaminated meat he ate in his native Mexico.

Golovkin plans to leave nothing to chance in the rematch, vowing to win inside the distance.

"If Canelo gives me a chance and fights like he claims he will, I will knock him out," Golovkin said.