Five division world champion Floyd Mayweather has verbally erupted in the direction of Mexican superstar Canelo Alvarez, who was very critical of Mayweather in a recent interview with TMZ.

Mayweather has been discussing the idea of a comeback, to fight Khabib Nurmagomedov - after he was recently challenged by the UFC lightweight champion.

Khabib challenged Mayweather over the weekend, after coming face to face with Mayweather's company CEO, Leonard Ellerbe, at a boxing event in Russia.

Khabib successfully defended his title earlier this month at UFC 229 with a submission win over Conor McGregor, who stepped out of the octagon and into the boxing ring last August to take on Mayweather.

McGregor lasted 10 rounds, with Mayweather ultimately breaking him down and stopping him - to raise his perfect record to 50-0.

Mayweather retired after the McGregor fight, but now he's pondering the idea of a comeback against Khabib and then a rematch with Manny Pacquiao.

Canelo, who was dominated by Mayweather over twelve rounds in 2013, has been eager to get the opportunity for revenge.

In the opinion of Canelo, Mayweather taking part in contests against UFC fighters like McGregor and Khabib are only hurting the sport.

If Mayweather wants a real return, Canelo is urging him to do the right thing - make the rematch.

"He wants to continue hurting boxing by making fights that don't make sense ... and not giving boxing the credibility it deserves," Canelo tells TMZ Sports.

"If he wants to return, I ask him to look my way to give a great fight to the fans. Let's do the second fight. It's very important. We have something pending there, so let's make the second fight."

Mayweather says Canelo was the easiest fight of his career. And says Canelo is a "cheater" - which is a direct shot at the boxer testing positive for the banned substance clenbuterol earlier this year - and saw him get suspended for six months by the Nevada State Athletic Commission.

And he also threw water at Canelo's 11 fight, $365 million deal with streaming service DAZN.

"It didn’t matter if Canelo ate his PED steak or not this night, this was by far the easiest fight of my career," Mayweather said on social media.

"Connor McQuitter was a way better fighter than Canelo's cheating ass and I beat the breaks off him too! It takes me 36 minutes or less to make $300 million plus. It literally takes me 1 night and 1 fight to make what you might make in 5 years and 11 fights! So really, who's still winning? You do the math!"