Gennady Golovkin did not look his best, but the middleweight champion successfully defended his WBC, IBF and IBO belts in a curious TKO win over Kell Brook at 02 Arena in London on Saturday.

The fight was stopped when Brook's corner threw in the towel with 1:06 remaining in the fifth round after Brook was absorbing some hard punches. Golovkin (36-0, 33 KOs) was thoroughly dominating the fifth round, landing several combinations with Brook hanging on the ropes.

But Brook (36-1, 25 KOs) didn't seem in serious jeopardy of being knocked out. The Sheffield native, who was making his debut as a middleweight, was competitive for much of the bout though his right eye was noticeably swelling. 

International Business Times scored the fight even after four rounds.

After the fight, Golovkin said Brook was not a true middleweight and that "it was not boxing," describing the bout as a street fight.

And the Kazakh was not particularly proud of his own effort. Golovkin described his performance like it was a "sparring" session.

"He was trying too hard to knock Kell out," Golovkin's trainer Abel Sanchez said. Sanchez, who agreed with the decision by Brook's corner to stop the fight, felt that Golovkin should have used his jab more. 

Brook said he "absolutely" could have carried on with the fight, and also described Golovkin as a "warrior."

He did, however, admit that his right eye was swelling and that it influenced his performance. Brook's trainer, Dominic Ingle, claimed that the eye injury was too much of a hindrance against a boxer of Golovkin's stature. Brook added that he was frustrated with the outcome and felt he had "so much more to give."  

"I believe I would have took over the middle to the last part of the fight," Brook said.

Golovkin, meanwhile, maintained his position that he wants to fight another British boxer, Billy Joe Saunders, who is the only other middleweight champion.

"I'm open for everybody, [but] I want a unification fight. I would like Billy Joe Saunders, first of all, because he has the WBO belt," Golovkin said.

Preview: Gennady Golovkin (35-0, 32 KO's) makes his 18th consecutive title defense and seeks his 23rd consecutive knockout when he faces British star Kell Brook (36-0, 25 KOs), a welterweight champion, who will have the crowd on his side at London's 02 Arena. 

The big storyline of the fight is Brook making his debut at 160 pounds. The Sheffield native is jumping two weight classes to fight arguably the best pound-for-pound boxer in the world.

This fight presents both boxers with their biggest challenge. Golovkin's biggest victory was over David Lemieux, while Brook held off star fighter Shawn Porter in a majority decision. 

Golvokin, 34, has great knockout power, while Brook, 30, can expect to fight with a more defensive presence. Both boxers are undefeated, Golovkin is considered the heavy favorite at -600 compared to Brook's +400. 

In the tale of the tape, Golovkin and Brook each had the same arm length, but Golovkin is listed at 5'10.5, just a bit taller than Brook at 5-foot-9. Brook weighs in at 159.4 pounds, while Golovkin weighs in at 158.9 pounds.

Coverage begins at 5:30 p.m. ET, but the title bout was reportedly set to begin at about 5:50 p.m. The referee is Marlon Wright of Canada. The judges are Guido Cavalleri of Italy, Craig Metcalfe of Canada and Benoit Roussel of Canada.

Here is how International Business Times scores the Golovkin-Brook fight:

Round 1

Both boxers looked active in the opening minute. Golovkin landed an excellent body shot that rattled Brook. Later in the round, Brook seemed to rally. Late in the round, Brook delivered a solid combination. But Golvokin looks like the better fighter.

Golovkin 10-9

Round 2

Brook seems content going toe-to-toe with Golovkin. It's been GGG in the center of the ring and pursuing Brook. Brook landed some good punches, particularly an uppercut. Crowd is energized by Brook's activity.

Brook 10-9

Round 3

There is some swelling on Golovkin's left cheekbone. Brook slips in the first 20 seconds. Golovkin looked urgent in the opening minute, seeking a knockout sooner rather than later. GGG had a hard right hand land midway through the round. Brook landed several good punches inside the final minute. Entertaining fight.

Golovkin 10-9

Round 4

Golovkin took some good punches, but it is Brook's face that is bruised. In the final minute, GGG seemed to hold back. Brook landed some decent punches.

Brook 10-9

Round 5 

Golovkin spent the first minute of the fight pounding on Brook, but Brook lifted his arms as if to say that he is not hurt. Brook is gambling by accepting these punches midway through the round.

The fight is stopped! Brook's corner throws in the towel at the 1:06 mark as Brook seemed to just take a bunch of hard shots. It's a bit confusing since Brook didn't seem hurt enough to quit. The London crowd went silent in bewilderment. It's hard to understand why Brook's corner felt he couldn't continue.

Golovkin wins in TKO.