Gennady Golovkin has revealed his fight with Saul 'Canelo' Alvarez could be his last if their rivalry does not develop into a series.

Their WBC, WBA, IBO and IBF middleweight unification match-up at Las Vegas' T-Mobile Arena on September 16 has long represented the most enticing head-to-head for the boxing purist.

Victory would also prove each man's finest hour in the ring, and could even be the 35-year-old Golovkin's last a fighter.

Should the Kazahkstani win, he will have established himself as one of the finest middleweights in history and, at a time when observers believe he is showing signs of decline, he could choose to call it a day.

"Maybe after this fight, I'm finished," said Golovkin, whose retirement would deny Britain's WBO champion Billy Joe Saunders a potential high-earning fight. "Maybe not. I feel very good.

"Okay I'm 35 but I feel like I'm 25. But this is boxing, not soccer, it's not a game, this is a fight and every fight is very difficult."

The undefeated Golovkin's aggression and ability, which has ensured 33 stoppage victories from his 37 fights and that he has fought for 12 rounds only once, has built his popularity in Mexico.

In 26-year-old Alvarez he is facing their most-loved active fighter, but, asked if he is risking his own popularity there, he responded: "I don't know, seriously, I remember my fight with Kell (Brook, in London), I come to the ring, 'Boo'. Couple of rounds (later), 'Okay, applause'.

"For me it doesn't matter, American guy, Mexican guy... I love sport. We go to the ring for boxing, it's sport for us, not political. Not 'I kill you because you're Mexican'. No, this is crazy.

"I know Mexican people, the same like UK people; everybody understands boxing, everybody loves boxing."