Sources: Canelo-GGG III talks have slowed down

One thing is clear: Unified middleweight world champion Canelo Alvarez's next fight is pegged for Sept. 14, the Mexican Independence Day weekend on which he usually fights.

Who boxing's biggest star will fight remains up in the air, however, as talks for a third fight with former unified middleweight world champion Gennady Golovkin have bogged down, sources have told ESPN.

The key sticking point is the site. Golovkin has made it clear that after an extremely controversial draw in their first fight in September 2017 and a disputed majority-decision loss in their rematch last September that cost him his belts and ended his reign tied for the division record, with 20 consecutive defenses, he has no desire to return to Las Vegas for a third fight, feeling that he did not get a fair shake in boxing's capital.

Las Vegas, however, is where Alvarez intends to fight, specifically at T-Mobile Arena, which hosted both bouts with Golovkin and where they generated more than $50 million in ticket sales between the two fights.

So even though both fighters are interested in the third bout and DAZN, the sports streaming service that has both fighters under nine-figure exclusive contracts, is pushing hard for the third fight to be finalized, Alvarez could go in another direction.

Alvarez (52-1-2, 35 KOs), 28, of Mexico, and his team have mentioned pursuing dangerous fights with either super middleweight world titlist Callum Smith (26-0, 19 KOs), 29, of England, or even light heavyweight world titlist Sergey Kovalev.

As much of a size advantage as Smith would have over Alvarez, Kovalev (33-3-1, 28 KOs), 36, a Russia native fighting out of Los Angeles, would loom as a far bigger man. Kovalev has a mandatory defense due against Anthony Yarde, but Eric Gomez, president of Golden Boy Promotions, which promotes Alvarez, said Alvarez is not joking when it comes to that possible fight.

"Canelo absolutely is serious about fighting Kovalev, and I think it would be a great fight," Gomez told ESPN. "All I can say is that Canelo is serious about making history and fighting him. Canelo always wants to fight the best opponents and the biggest fights. I think Canelo is the best fighter in the world, and I think anywhere between 160 and 175 pounds, he will give anyone a run for their money."

Main Events CEO Kathy Duva, Kovalev's promoter, said a fight with Alvarez is certainly one their side is interested in.

"I do believe, based upon what I am hearing, that Canelo really wants to fight Sergey," Duva said. "It's a legacy thing. But Golden Boy has not made us any kind of offer. So unless and until they do, there is nothing to talk about. Having said that, you have to really admire Canelo. The guy is truly a throwback fighter, always looking for a bigger challenge. I really admire that about him. And, of course, Sergey would love it too."

Alvarez has fought as heavy as the 168-pound super middleweight division twice. In 2017, he weighed the contract limit of 164 pounds in a shutout decision win over Julio Cesar Chavez Jr., and in December he was 167ΒΌ pounds when he knocked out England's Rocky Fielding in the third round to win a secondary super middleweight world title before returning to the middleweight division for his unanimous decision win over Daniel Jacobs to unify three belts on May 4.