Golovkin beats Brook in fifth round at London's 02 Arena
Trainer Dominic Ingle throws towel in
Unbeaten pair fought for WBC & IBF middleweight belts
Haskins beats Hall to retain IBF bantamweight title
Steve Bunce
Boxing pundit on BBC Radio 5 live
Kell Brook looked tense in the dressing room. Now he's coming to the ring with that look on his face. It's the face that says I'm ready and I'm ready to fight.
We mentioned the last man to climb from welterweight to middleweight and take a world title, that was Emile Griffith. So, how did he do it?
Virgin Islander Griffith won and lost the world welterweight title several times in the early 1960s, while earning unfair notoriety for killing bitter Cuban rival Benny Paret in 1962, in a bout that was broadcast live on American television.
In 1966 Griffith vacated his welterweight title to challenge Nigeria's middleweight world champion Dick Tiger, who had won the title from American veteran Joey Giardello only six months earlier.
Despite being outweighed by 10lb, Griffith floored Tiger for the first time in the Nigerian's career in round nine before being awarded a narrow decision. The Madison Square Garden crowd booed and 17 out of 22 boxing writers perched ringside thought Tiger had won, but the record books state the opposite.
Image source, Getty ImagesEyes on the prize: Griffith in a London jewellery shop in 1964
Ben Dirs
BBC Sport at O2 Arena, London
Right, now for the main event. I think we'll find out almost everything we need to know in the first couple of rounds - can Brook hurt Golovkin, does Golovkin punch way harder than anyone Brook has faced before and is Golovkin as good a boxer as Brook.
If the answers are 'no', 'yes' and 'yes', then Brook doesn't really stand a chance.
Has promoter Eddie Hearn been reckless by allowing one of his prized assets, Brook, to jump two weights and fight the destroyer that is Golovkin? Hearn, predictably, doesn't think so.
"You can't just defend your world title against mandatory challengers in Sheffield," he said. "Now there is an acceptance from fighters and their teams that they have to be in big fights.
"It's my job as a promoter to look at the different opportunities, present them to a fighter and say, 'You're one punch away from becoming the biggest star in world boxing. Go and do it, son, and you'll change your life forever.' Kell's a big boy, an unbeaten world champion. He's not a six-round novice."
Image source, Getty ImagesJust one month after he was crowned world champion, Kell Brook found himself with a very different fight on his hands.
Having beaten Shawn Porter to win the IBF welterweight title, Brook was enjoying some downtime and a holiday in Tenerife when he was stabbed in the leg with a machete on a night out.
It wasn't the first time the Sheffield boxer had suffered such a fate either, having been stabbed in his home city back in 2007.
But Brook wasn't down for long. Following the incident in September 2014, where he "lost a lot of blood", Brook was back defending his title in March with a fourth-round stoppage of Romanian-born Jo Jo Dan.
Golovkin's record is scarily impressive. The deadly Kazakh has stopped his opponent in each of his last 22 successive fights.
The last time GGG was forced to go the distance was in June 2008, when he beat Algeria's Amar Amari by unanimous decision in an eight-round bout.
The quality of the 34-year-old's opposition has often been called in to question, but the trouble with being so ruthlessly destructive is no one wants to step into the ring with you.
Take Saul 'Canelo' Alvarez, for example. The Mexican relinquished his WBC middleweight title after failing to agree a bout with GGG by the required deadline earlier this year.
Image source, Getty Images
Mike Costello
Radio 5 live boxing correspondent
Image source, ReutersThe party is getting started. There's a commotion at the other side of the ring as Zlatan Ibrahimovic takes his seat, having arrived after playing in the Manchester derby earlier on.
Brook has spoken about his desire to emulate Sugar Ray Leonard, who came out of retirement to beat Marvin Hagler in 1987.
But can the Sheffield man use welterweight great Leonard's comeback against the middleweight champion as inspiration?
"I want to do what Leonard did with Hagler - use my speed, my footwork and box the perfect fight," said Brook.
"I do fear him. Of course I do. I know he's a big puncher and that nobody wants to fight him for a reason.
"But the fear is positive because it's going to make me super-sharp with cat-like reactions."
Image source, APSugar Ray Leonard, pictured with Muhammad Ali, in 1982
Back to the main event tonight then....
Kell Brook's team believe their man will be more than comfortable at 160lb, and it is certainly true that the 30-year-old was a heavy-set welterweight.
In fact, weighing in at 159.4lbs, Brook was slightly heavier than Gennady Golovkin who tipped 158.9lbs.
Image source, Getty ImagesLee Haskins: "It's hard not to tire against someone like Stuart. I feel like I was winning the fight clearly with my shots.
"You try boxing this guy, he just keeps coming forward, forward, forward. He's like a pitbull. he hits very hard.
"I'm not here to show I'm the toughest man in Britain. I'm here to win fights and get paid."
Haskins v Hall
Stuart Hall: "I thought I could have edged it but I think I started a bit late, I thought it was closer than the points said.
"It was close, but I started too late. (A third fight) would be good if I could get it."
Haskins v Hall
Image source, ReutersWell, having not touched gloves between the rounds all fight, Lee Haskins embraces Stuart Hall at the end of round 12 with a show of respect - but both men think they've won it.
Who will be taking home the IBF bantamweight belt tonight...
It's Haskins, the Bristol man has successfully defended his title for a second time after getting the judges' decision, albeit with boos ringing out around the O2 Arena.
Mike Costello
Radio 5 live boxing correspondent
There are two key factors which will settle the outcome: how Brook adapts to the heavier poundage and in particular his resilience to harder punches than he has faced before.
And how much he genuinely feels he can win; does he really believe what he has been saying with such force in the build-up?
Your Brook v Golovkin predictions
Andy Holden: A good big man always beats a good little man. GGG wins whenever he decides to.
Angry Man: My prediction is Golovkin in the 8th, Brook will box smart but eventually get caught.
Timirlan Dzaurov: It's 3 am in Kazakhstan, yet the whole nation is up for the massive fight! Make us proud GGG!
Haskins v Hall
Image source, Getty ImagesWell, Hall is really going for this one. No sign of him tiring heading into the final round and Haskins, having looked comfortable early on, could now be in a bit of trouble.
It's Hall in control, and the Darlington man lands one to his opponent's body that sends him against the ropes. The IBF bantamweight champion is slowing, but by no means out of it.
Brook says taking on middleweight king Gennady Golovkin is like "David versus Goliath"
"I'm entering unknown territory but I'm full of energy and will be explosive with the extra pounds," added the Sheffield fighter.
"There's a lot of politics in boxing and it's destroying the game. And if you can't get massive fights at your weight, you may have to jump a division or two.
"I'm a world champion, I've beaten everyone I've been in with and I want to test myself. I haven't got years and years left so I want to compete against the best."
Image source, Getty ImagesKell Brook will be hoping to win Gennady Golovkin's WBC and IBF titles tonight, but the 30-year-old will not get a shot at the Kazakh's WBA belt.
Many observers have described the bout as a mismatch, and with that in mind the WBA has refused to sanction the fight, stating it is concerned about the Sheffield fighter's health.
Image source, Getty ImagesHaskins v Hall
Image source, ReutersThe eighth round looked like Stuart Hall's best so far, he's grown into this one since that little ticking off by his corner.
Lee Haskins surely took the early rounds, but Hall - at 36 - is not about to let what must be his final shot at a world title slip from his grasp without giving it a serious go.
Apparently the Golovkin camp weren't happy with the tape Kell Brook has had his hands wrapped with - because it was green.
The officials have checked it over, however, and given it the thumbs up. No re-wrap for the Sheffield man required.
Your Brook v Golovkin predictions
Greg Fearon: GGG late on, tenth round perhaps. Should be a corker!!
Stuart Joszko: Going up two weights catches up with you later in the fight. GGG in 8.
Smiffy1875: Would love brook to win it! But I think golovkin will win in 3rd or 4th!