Kevin Mitchell added the British super-featherweight title to his Commonwealth belt by stopping Carl Johanneson in the ninth round.
Mitchell had to dig deep for his win
Mitchell, 23, stretched his unbeaten run to 26 bouts, but had to dig deep.
Johanneson bounced back from a slow start to increasingly bully Mitchell with his tidy and powerful work and nearly had his man down in the sixth.
But Mitchell caught a second wind and dropped Johanneson in the ninth before applying an impressive finish.
"I came of age tonight. He's a brilliant champion and I've beaten him," said Mitchell, boxing on the undercard of the David Haye v Enzo Maccarinelli fight.
"It was a brilliant win for myself."
Mitchell did show resilience to take the victory, but critics may question two or three tired rounds in the middle of the contest when he could have lost his unbeaten run and his belt.
The Commonwealth champ brushed the canvas in round six after a heavy attack from durable Johanneson and wobbled on other occasions.
I learnt more in that fight than in my previous five or six
But he regrouped and caught his opponent with a big shot to get the knockdown, immediately swarming his foe to secure a stoppage win.
It was easily the most significant win of Mitchell's 26-fight professional career but it also revealed some glaring flaws in the his armoury.
Mitchell said: "You always hope you've got the heart as a boxer but you never know you have until you've been hurt and you've come back from it.
"Early on I had it all my own way, but Carl's a brilliant fighter who has beaten everyone at British level and I knew that after three or four rounds he ups his game and starts stepping up the pressure.
I was getting too close to him and playing into his hands but after four rounds of doing that I got back to what I do best, boxing, moving, long left hooks, left upper-cuts and it started working for me again.
"You haven't seen the best of me yet, nowhere near it. I learnt more in that fight than in my previous five or six ? I learnt to dig in deep, I learnt I had a lot of heart and not to switch off."