Both men stand in opposite corners of the ring. The Kazakhstan flag is held up behind Gennady Golovkin, the Mexican flag is waved behind Saul 'Canelo' Alvarez's head.

Time to see what's what. No more chat.

But, probably plenty more controversy.

Mike Costello
BBC Sport boxing correspondent on Radio 5 live

Image source, .

"I am looking forward to this as a fan as I just do not know who is going to win this fight. Some fights do keep you swaying.

"There won't be the same sort of outcry in boxing or in the US as there is in athletics as the attitude to drugs is different. It may be hardening but it is not anywhere near what it is in athletics.

"The key thing is that the Voluntary Anti-Doping Association (VADA) tests now are unannounced and they just turn up during camp. The next big thing is for fighters to be tested outside of competition training time. Once the fight has been signed they can sign up to testing and tests can happen. But all of the time outside of that window they can take what they like, when they like, and those substances can have long-term beneficial impacts."

Image source, BBC Sport

A hot topic of this fight is the fact that Alvarez returned two positive tests for Clenbuterol that postponed the original fight in May.

The Mexican's excuse was that he ingested contaminated meat but still served a six-month ban.

"A top golfer banned for the same period would have missed all four Majors, a leading tennis player two Grand Slams," says the BBC's Mike Costello in Vegas.

" Canelo, ultimately, has missed zilch with the rematch being rescheduled for this weekend.

"The snag for those keen to shred Canelo's credibility is that cases involving contaminated meat in Mexico are notorious in sport. He accepts he should have done more research - so was he unlucky and is he banking on precedents to help salvage his reputation?"

Matt Edgley: coffee ready, radio on, TV on with sound down. Waiting for Mike Costello. GGG in 10. A lot more anger here. That's in GGG's favour.

Who else is up? Tweet us on #bbcboxing.

Darkness in the arena. The star of the show - love him or hate him - is about to set foot before the masses.

He wears black with the word 'Mexcio' across his chest. Mexican music plays and the screams go up.As he steps out from the walkways in the arena, flags wave, camera phones point at him everywhere you look...

I'd argue that last time out, Saul 'Canelo' Alvarez was the cool one. The composure he showed to stay on the ropes and invite a brutal puncher on to him was borderline crazy yet stunningly brave.

But who am I to argue with a man who can knock in a 147 in the time it takes me to make a brew.

Some social media air time (for what it's worth) has been devoted to footage of Saul 'Canelo' Alvarez collapsing on to a stool after weighing in. But did he? There are those saying he simply slipped on his way to sitting down.

Anyway, Liam Smith - who lost to Alvarez in 2016 - believes the latter. Encouragingly, he thinks we may be in for a treat.

Demetrius Andrade
Former light middleweight world champion on BBC Radio 5 live

Golovkin looks like he's ready to rumble. Rumble young man, rumble!

Gennady Golovkin is leaving his dressing room.

"Set to make his way to the ring.... here is TRRRIPPPLLLEE GGGGGG", shouts the ring announcer.

The White Stripes 'Seven Nation Army' plays to bring him in as the lights go out and strobe lights run wild....

Demetrius Andrade
Former light middleweight world champion on BBC Radio 5 live

Canelo's a good fighter. Golovkin's a good fighter but the winner of this can become a great fighter and a wanted man among the rest in the division.

BBC Radio 5 live

As the fighters get ready to leave their changing room, commentary has kicked in on BBC Radio 5 live. Tune in by clicking play at the top of this page.

Commentator Mike Costello is joined by Demetrius Andrade - who takes on Billy Joe Saunders in a few weeks for the WBO world middleweight title.

Doncaster's finest (well, join finest with his twin brother Jamie who also boxes at world level) is very much a Gennady Golovkin fan tonight.

McDonnell gets his second world-title shot against Daniel Roman on 6 October by the way.

In the run-up to a big fight, the final head to head can get a bit fiery.

Alvarez and Golovkin had to be separated by their teams on Friday after they both clashed a bit too close.

Watch below.

I can tell you Saul 'Canelo' Alvarez has just put the garment on which he will wear to the ring. So we are moments away...

Jack Davenport
BBC Radio 5 live in Las Vegas

A bit of a misjudgment by the promoters as all three fights on the pay-per-view undercard ended early so they've had over an hour to fill.

Roy Jones Junior - working for the host broadcaster - has had to earn his money and do plenty of talking. The biggest cheer of the night so far has gone to Denzel Washington when the Hollywood actor was announced to the crowd.

Image source, .

A capacity 20,000 are expected at the T-Mobile Arena in Las Vegas. If you've never been I can tell you it's a great venue which is about 100 metres off the main strip in Sin City. No taxis or long walks needed.

Those who got into the arena early for this one will have been disappointed though as the undercard stank like gone off milk. Ireland's Gary O'Sullivan was knocked out by David Lemieux in a round shortly before Jaime Munguia wiped Brandon Cook out in three rounds.

A few cameras are following Saul 'Canelo' Alvarez tonight. He looks as chilled as an ice cube.

A huge Mexico flag is on the wall behind Saul 'Canelo' Alvarez in his dressing room as he goes through a bit of shadow boxing. Ducking, weaving, his eyes scream focus.

Remember, it is Mexico's Independence weekend.

Some 123 million people reside in the country and a huge portion of them will be glued to this.

Steve Bunce
BBC Radio 5 live boxing pundit

Last year it was the fight that would save boxing after the McGregor v Mayweather bout, when people said the lunatics had taken over the asylum.

They put on a fantastic spectacle, it was gripping and you couldn't take your eyes off it. I still think Adalaide Byrd's score is the worst single score that I have seen in my time in this business.

Now here's a man who could make middleweight having campaigned in the division back in 2016.

Do you agree with his prediction? Tweet me on #bbcboxing.