Spinks (right) had a tough fight on his hands with Karmazin

Spinks was scored the 115-113 winner by two judges in St Louis while the third had the fight a 114-114 draw.

The 28-year-old, the son of former heavyweight champion Leon Spinks, said: "People didn't believe in me but I always knew I could do it."

Spinks lost the undisputed welterweight title to Zab Judah in his last fight nearly 18 months ago.

He added: "There's no quit in my heart. I never doubted my talent. I proved everybody wrong. I'm a champion once again."

Unfortunately it did take me until about the seventh round to figure out how to work with him Roman Karmazin

Karmazin, whose last fight was when he clinched the title a year ago, complained that the referee had prevented him working inside in clutches.

"With this type of referee I could not have won that fight," Karmazin said.

"Unfortunately it did take me until about the seventh round to figure out how to work with him. I was running around.

"He knew he was ahead after seven rounds and he had to stay on his feet. He was tough to catch running around."

Spinks said Karmazin's style had made the fight difficult for him.

"He is so awkward and he's strong. He keeps hanging in there. He's a great champion," Spinks said.

In a very close fight, both men landed telling punches in the early rounds, before Karmazin began to put together combinations in the middle rounds, to which Spinks responded with jabs and flurries.

A four-punch combination from Karmazin capped by a right-cross had Spinks stunned late in the 10th, and he had to hang on to make it to the end of the round.

But Spinks fought back in the final rounds to claim the fight.