ATLANTIC CITY, N.J. -- Unbeaten and unknown heavyweight Derrick Jefferson wanted to make a statement. He did.

The 31-year-old from Detroit scored a thunderous sixth-round knockout over pinch-hitting challenger Maurice Harris on Saturday night in a scheduled 10-round non-title fight.

Jefferson (22-0) knocked down Harris twice in the second round but appeared to be struggling with his stamina and couldn't finish him. Harris knocked down Jefferson with a short left later in the round.

But at 2:52 of the sixth, he connected with a left hook that knocked Harris onto his back. Harris, 23, of Newark, looked like he was out before he even hit the canvas. Ringside physicians jumped into the ring within seconds to examine him, and he got up after about two minutes.

"I thought I was ready to take him out, but he got me real good," he said. "It was just when I thought I had him."

Harris, who is beginning to fashion a career as a last-minute substitute, stepped in last week after Jefferson's original opponent, Lance "Mount" Whitaker, was scratched after injuring a knee in training.

He appeared to be the more well-conditioned fighter and connected on many rabbit punches while the wild-swinging Jefferson tried to knock him out.

But Jefferson, a 6-foot-6-inch, 246-pound former basketball player who didn't start boxing until he was 27, put Harris away before he ran out of steam. He got $75,000, Harris $100,000.

Harris dropped to 16-10-2.

"I'm devastating," Jefferson said. "Don't make any mistakes against me.

"I knew if I knocked him down one more time, he wouldn't get up. And he didn't."

The fight, at Convention Hall, was a co-feature with heavyweight fight between Oleg Maskaev and Hasim Rahman.