Steve Bunce
Boxing pundit on BBC Radio 5 live

We saw one of the greatest modern fighters forced to go toe to toe. He had to fight in every round. Kell Brook refused to wilt.

Image source, Reuters

So it's Gennady Golovkin's by TKO, taking him to 23 consecutive wins by knockout and 36 in an unbeaten career in total.

Image source, PA

Wow, well Brook looked almost surprised when he spotted Ingle waving the towel. But the trainer could see his man taking a beating and knew he couldn't have taken much more.

Kell Brook stood up to Golovkin, but in the end it wasn't enough. Stepping up two weights was always going to be a monumental task and after earning GGG's respect a round earlier it seems the Kazakh realised he had to do something to stop Brook. And he did, in ruthless fashion.

Image source, Getty Images

Here goes Golovkin, body shot after body shot that thud into the gut of Brook who needs to quickly get away from the ropes.

Brook enjoys a brief reprieve, he's standing up to GGG, but each time he does the middleweight fires back.

And there comes the towel from Brook's corner, it's over. Trainer Dominic Ingle furiously waving away as Brook continues to take a barrage of GGG punches, and it's stopped. It's over for Brook.

David Haye
Former world heavyweight champion on BBC Radio 5 live

Image source, Getty Images

I gave that round to Triple G but Kell Brook has covered himself in glory tonight. He is really and truly in the fight. He's proved a lot of people wrong.

Well Golovkin may be on top but he is being tested by Brook, who is so far withstanding each flurry of punches that comes his way.

Brook bravely steps into the centre of the ring and looks to take it to the middleweight champion, but anything that makes it through Golovkin's stance barely seems to trouble the 34-year-old.

Brook catches GGG with a left, and the Kazakh almost acknowledges it with a nod towards his opponent. But each reply from Golovkin lands with such ferocity and he's the one finding the eye-catching punches.

David Haye
Former world heavyweight champion on BBC Radio 5 live

Kell Brook started looking busted up in the last minute of that round. Taking punches really does sap your energy stores.

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Brook stumbles in the third, just a slip it looked like, and he's quickly back on his feet to face up to Golovkin.

Golovkin has started lively and goes after Brook with a jab, followed by one to the body. Brook's eye looks to have been caught, and having rocked the Kazakh in the second it's Brook on the back foot in the third.

GGG works his man into the corner, but Brook is determined to squeeze out and attempts to hit back. What intensity from these pair, these first three rounds have flown by.

Steve Bunce
Boxing pundit speaking on BBC Radio 5 live

One of the finest three minutes we have seen. That was pure quality. I think that was Brook's round.

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Gennady Golovkin lands another strong right hand on Kell Brook early in the second, and his defence holds firm as the Brit looks to edge his way back in.

Good attack from Brook, but he's not yet moving the Kazakh who continues to step into Brook and attempt to find his range. 

A couple of wild swings going missing, and Brook grows into the round as an upper cut, followed by a three-punch combo gets the crowd going. Much better from the challenger.

David Haye
Former world heavyweight champion on BBC Radio 5 live

Golovkin walked through Brook's punches and landed at will, while Kell's shots bounced off him towards the end of the round.

GGG is straight on the attack, before Brook lands a jab that barley moves the Kazakh fighter.

And it's Golovkin that is firing shots into Brook again, opening up and sending the challenger towards the ropes in the first round. What power from the middleweight champion.

Brook has slipped a couple through the defence of his opponent  towards the end of the round, but Golovkin isn't moved.

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What a sound coming from inside the O2 Arena as the first round begins in London. 

Vincent Watts: GGG will adjust to the speed and it won't go past 3, as much as I hate to say it..

Jarleth Eaton: There aren't many better things in sport than hearing Michael Buffer say: "LET'S GET READY TO RUMBLEEEEEEEEEEEE!"

Kenny Jarvis: Desperate for a Brook win, my head is trying to find a way to match my heart, but I just can't see it.

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Kell Brook stays poker faced, eyes on his opponent, as the crowd and his backroom team belt out the national anthem, before the world champion breaks out into a little clap.

GGG pulls one of those golden gloves to his chest as the Kazakh anthem is played, he looks calm and collected.

It's nearly fight time....

David Haye
Former world heavyweight champion on BBC Radio 5 live

There's a supreme confidence emanating from Triple G tonight. Golovkin walked to the ring without a care in the world.

'All of the Lights' by Kanye West is Brook's choice to enter the ring, and now it's Triple G's turn.

He won't be fazed by sections of the crowd who have a little boo. Those are soon shut down, as 'Seven Nation Army', as always, accompanies the most feared middleweight in the world in the ring for his first fight in London.

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Kris Catley: 'Kell Brooks on fire, GGG is terrified' Quality chant from the crowd.

Coolj3t: Think we need to see how well Kell takes Golovkin power but I'll have go with my fellow Brit and say decision to Kell.

Peter Coleman: I hope that I'll be proved wrong but I think Brooks is kidding himself. Two weight divisions is too much.

Image source, Reuters

The lights go down in the O2 Arena, the countdown begins, and here comes Kell 'Special K' Brook.

If they weren't already, the nerves will be kicking in now for the Sheffield fighter who has stepped up two weights to fight the unbeaten middleweight champion.