Michael Jennings suffered the first defeat of his professional career as Young Muttley took the British welterweight title in Nottingham.
Muttley celebrates his hard-earned victory over Jennings
Jennings looked like he had done enough to win in the second defence of the title he won last year.
But the West Bromwich puncher Muttley won it on a split decision victory.
"I was very surprised when I heard the decision. I knew I had the strength and in training I worked harder on my fitness," said 29-year-old Muttley.
Promoter Frank Warren will now push for a rematch clause to be invoked.
Although Muttley started cautiously, a sharp left-hand counter stopped the champion in his tracks midway through the second round.
Muttley continued getting through with occasional lefts while Jennings failed to threaten despite showing smarter boxing skills.
Although Muttley appeared to tire badly midway through the fight, he got his second wind in some style, trading good clean left hooks in the ninth and nicking the 10th to set up a grandstand finish.
Muttley edged a tight verdict 116-113 on two of the judges cards, while judge Howard Foster favoured Chorley man Jennings 115-113.