Terence Crawford defended his WBO welterweight title with a stunning fourth-round knockout of Kell Brook on Saturday.

The American improved his impeccable record to 37-0 with a flurry of power in the fourth round at the MGM Grand in Las Vegas.

Crawford left Brook staggering with a big right and followed it up to end the fight and keep his WBO welterweight crown.

Brook (39-3) had shown good early signs back at welterweight in what may end up being his last professional fight, but Crawford's power proved too much.

Defending for the fourth time but fighting for the first time in almost a year, Crawford made a slow start.

Brook, a former champion back at welterweight for the first time since 2017, dictated with his jab early, and landed a nice uppercut in the second round as he troubled Crawford.

Crawford, though, found his rhythm late in the third, landing a big right hand in what was a sign of things to come.

And the bout did not last much longer.

A huge right from Crawford sent Brook stumbling into the ropes, and he followed it up with a left-right combination to end the fight.