Kell Brook retained his IBF welterweight belt when mandatory and outclassed challenger Jo Jo Dan threw in the towel after their fourth round and four knockdowns on Saturday.

Brook remained unbeaten after his 23rd knockout win in 34 fights.

Only six months ago, he was attacked on holiday in Tenerife, stabbed in the thigh with a machete by an assailant yet to be caught. He needed 60 stitches.

Dan might need a few, too, after he was put down twice in the second round and twice more in the fourth.