Spence Jr stops Brook in 11th round
George Groves beats Fedor Chudinov to win the vacant WBA world super-middleweight title
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But this was certainly no holiday for Brook. Oh, by the way, while in Fuerteventura, Brook also did this...
Image source, Lawrence Lustiglots of this...
Image source, Lawrence Lustigplenty of this...
Image source, Lawrence Lustigand don't forget about this.
Image source, Lawrence LustigIn the build-up to this fight, Kell Brook took the chance to get some sun in Fuerteventura.
Looks nice.
Image source, Lawrence Lustig
Luke Reddy
BBC Sport boxing reporter at Bramall Lane
Image source, .A wander around this famous old stadium reveals a few areas where it may be aching with fatigue but every banner and sign spits out Sheffield pride regardless.
At one end of the stadium, just above where a goal post would stand normally, there's a banner which reads "forged in steel".
The consensus ringside is that Brook will need to be built from such material tonight. A few journalists have analysed his body shape after the big weight cut and there are concerns he may run out of gas if this goes down the stretch.
Boxing can be a brutal, painful business. And Kell Brook knows all about that.
After his fifth-round loss to Gennady Golovkin in September, Brook needed orbital bone surgery, where they inserted a piece of titanium into his eye socket.
"They had to take my eye out," Brook said casually to BBC Radio 5 live's Boxing Podcast, as if it was just an everyday occurrence like getting a loaf of bread from the shops.
So is Brook worried about it? Doesn't sound like it.
"My surgeon said it is going to be as strong as it was before, having metal in there - I'm a bit like the Terminator," said the Sheffield Schwarzenegger.
Image source, Getty Images
Image source, Rex FeaturesFor the first time in his career, Kell Brook is coming into a bout having lost his previous fight.
However, he had jumped up two weights to take on WBC, IBF, IBO middleweight champion Gennady Golovkin, who is regarded as the best pound-for-pound boxer in the world.
It always looked a hugely ambitious task for Brook last September, but he did cause the Kazakhstan fighter some problems, before Golovkin won with a fifth round stoppage.
That loss was Brook's first in his 37-fight career. However, it did not cost Brook his IBF welterweight title, which is now on the line tonight.
Image source, Getty ImagesLuke Reddy
BBC Sport boxing reporter at Bramall Lane
Amir Khan entered the stadium a short while ago. His rivalry with Kell Brook is known all too well and to say there was a frosty reception for the former world champion would be an understatement. I can't state exactly what was chanted as it involved a cluster of swear words, but I guess you get the picture.
My guess is Khan will watch Brook box, then go in front of the cameras and talk the Sheffield fighter down in a bid to get a response and perhaps earn a few headlines tomorrow. It never hurts to have your name printed in this game.
Image source, Rex FeaturesAmir Khan is at Bramall Lane and he could well end up fighting the winner in the future.
A bout between Khan and Brook has long been talked about, long been anticipated, long been hoped for, but, for whatever reason, it has not happened yet.
Here's hoping it can do sometime soon.
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This was the scene in the away dressing room not too long ago.
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Chilled out? Kell Brook has tweeted this not too long ago.
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In case you were wondering, 'Chocolate Brownies' is the nickname Brook has given his fists. Sweet.
Spence will be hoping for a low-sugar kind of evening.
Right, what a night it has been so far. Now the main event. Kell Brook aims to retain his IBF Welterweight Championship against unbeaten and highly regarded American Errol Spence.
Image source, Rex FeaturesThis super-featherweight contest didn't last long either.
Cardiff boxer Joe Cordina caused Bexleyheath's Josh Thorne all sorts of problems in the opening round of their contest.
Thorne went to his stool after the first round and never got back in the ring with his corner citing damage to their boxer's ear. Again it was a bit controversial, with Thorne saying Cordina had hit him when the referee was separating the fighters.
Cordina, who won a bronze for Wales at lightweight in the 2014 Commonwealth Games, has also won all three of his professional bouts.
Image source, ReutersThis one appeared to be a cruiserweight mismatch.
Briton Lawrence Okolie managed a comfortable opening round win over Rudolf Helesic of the Czech Republic.
The 24-year-old, who has won all three of his professional bouts, dropped his opponent twice in the opening round, whose arms were flailing as he hit the deck.
Okolie competed at heavyweight at Rio 2016.
And the man himself has gone on to Twitter to defend himself...
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Image source, Getty ImagesAnthony Fowler recorded a win in his professional middleweight debut inside the opening round - albeit in controversial circumstances.
The 26-year-old - cousin of former footballer Robbie - struck opponent Arturs Geikins, who crumpled to his knees before the English boxer hit him again while the Latvian was in that position.
The referee decided not to disqualify Fowler. Geikins got up only to feel the force of a right hook to the body which saw him hit the canvas once more.
Fowler won Commonwealth gold for England in 2014.
Time for a very quick look at some of the other fights that have happened tonight.
Adam Booth
Former trainer of David Haye on BBC Radio 5 live
George Groves gambled. He was cut. He was ahead on points. He has that killer instinct. Even if it means sacrificing his plan, he just wants to get the job done. Chudinov was numb. He was just taking punches.
Some tweets from the world of boxing...
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George Groves, who has just won the Super WBA Super-Middleweight title, says: "What a tremendous atmosphere, I didn't know what to expect. I'm so over the moon.
"I kept hitting him and I thought I couldn't get rid of him. I would have carried on punching until everyone had left, I was not going to stop, I was not going to let this go."
Steve Bunce
Boxing pundit on BBC Radio 5 live at Bramall Lane
He's in tears George Groves and understandably so. It was 84 seconds of relentless boxing.
Mike Costello
BBC boxing correspondent at Bramall Lane
Carl Froch, the man who has beaten Groves twice in world title fights, stands and applauds. Respect all around the world of boxing for the man who kept trying and trying.