ATLANTIC CITY - Heavyweight Johnathon Banks has spent the bulk of his career serving as a sparring partner and co-trainer for heavyweight champion Wladimir Klitschko.

He may soon be fighting his friend.

Banks (29-1-1, 19 KOs) sent shock waves through the heavyweight division at Boardwalk Hall on Saturday night with a spectacular second-round knockout over formerly unbeaten Seth Mitchell (25-1-1, 19 KOs) on the Antonio DeMarco-Adrien Broner undercard.

Banks scored three knockdowns in the second round, prompting referee Eddie Cotton to halt the fight at 2 minutes, 38 seconds of the round. Banks dedicated his performance to the late trainer Emanuel Steward, who died on Oct. 25.

"I was very motivated for this fight in light of everything that has happened," Banks said. "I wasn't thinking of myself as an 'opponent' whatsoever. Mitchell is a big, tough, strong guy, but he couldn't handle me. He was not experienced enough to hold on or grab me and therefore I was able to continue to hurt him."

In the main event, Broner (25-0, 21 KOs) earned the WBC lightweight championship with an eighth-round TKO over DeMarco.

Mitchell, a former linebacker at Michigan State University, was heavily favored and was a crowd favorite. Six busloads of fans made the trek from his hometown of Brandywine, Md., to cheer him on. He got off to a strong start in the scheduled 12-round fight, using his size advantage - he weighed 242 pounds to Banks' 218 - to bull his way inside and land some overhand rights and body shots.

But Banks, a former cruiserweight, turned the momentum with a straight right early in the second round that dropped Mitchell on the seat of his Michigan State green trunks against the ropes.

Mitchell quickly got to his feet, but was clearly hurt. Banks kept up the pressure and sent Mitchell to the canvas again with a left hook-overhand right combination. Again, Mitchell managed to get up, but Banks unleashed another barrage and Mitchell toppled onto his side along the ropes. Cotton waved a halt to the fight as Mitchell tried to rise again, but fell back down.

"I could've gotten through the round, but the ref did what he had to do," Mitchell said. "I feel OK, he just caught me with a good shot.

"I'm really upset, but this won't spoil my dreams. It will set me back a little, but don't feel sorry for me. Feel sorry for my next opponent."

Mitchell was seeking his second straight victory at Boardwalk Hall. On April 28, he recovered from a rough start against Paulsboro native Chaz Witherspoon to score a third-round TKO on the Chad Dawson-Bernard Hopkins undercard.

Broner, a Cincinnati native, dropped DeMarco with a left uppercut in the eighth. While referee Benjy Esteves moved in to start counting, DeMarco's corner mercifully stopped it with one minute, 49 seconds left.

"I'm proud of DeMarco for fighting the way he fought," DeMarco's promoter, Gary Shaw said. "But Broner's the total package. He could be the next Floyd (Mayweather, Jr.)."

Broner punished DeMarco throughout, hammering him with uppercuts and hooks that produced welts beneath both eyes. Broner averaged 39 power punches a round. The lightweight average is 14, according to CompuBox statistics.

DeMarco hung tough for most of the fight. He refused to retreat and chose to try to land his own shots. He landed a few, but Broner gradually took command. By the end, a crowd that was cheering Broner's punches began to cringe at the onslaught.

"I was shaking and baking him until I flipped him up," Broner said. "I knew coming into this fight it was going to be a world-class fight. But I knew he didn't have the skills to beat me.

"I wanted to make a statment tonight and I did. He was definitely the toughest opponent I've faced. He was strong and could take a punch."

Golden Boy Promotions donated $2 for every ticket sold and $1,000 for every knockout on the seven-fight card to the Boys and Girls Club, which suffered extensive damage from Hurricane Sandy. Golden Boy president Oscar De La Hoya and host Caesars Atlantic City matched the donations.

All seven undercard bouts ended in knockouts or TKOs, thus raising $21,000 for the Boys and Girls Club.

Canadian junior-middleweight Phil Lo Greco (25-0, 14 KOs) registered a controversial TKO over Daniel Sostre (11-8-1, 4 KOs). Sostre dropped Lo Greco in the first round and was hanging tough until referee Alan Huggins stopped it in the seventh.

Philadelphia middleweight Demetrius Hopkins (31-3-1, 12 KOs) earned a fifth-round TKO over York, Pa.'s Joshua Snyder (9-8-1, 5 KOs). Philadelphia junior-middleweight Julian Williams (10-0-1, 5 KOs) scored a seventh-round TKO over Jonuel Tapia (8-3-1, 5 KOs), of New York. New York welterweight Zachary Ochoa (3-0, 3 KOs) knocked out Michael Salcido (1-5), of Casa Grande, Ariz. in the first round. White Plains, Md., lightweight Terron Grant (5-0, 3 KOs) scored three knockdowns in the first round to earn a quick TKO over Mexico's Abraham Esquivel (5-3, 3 KOs) in the opening bout.

PUNCHLINES: There was a minor controversy before the main event when DeMarco's camp complained that Broner's gloves were smaller. There was no scale to weigh the gloves in the dressing rooms - they are supposed to weight eight ounces - so DeMarco was offered the opportunity to wear the same gloves as Broner and he agreed. Both sets of gloves were pink.

Sam James of "The Voice" performed the National Anthem before the fight. ... Banks usually enters the ring to an Eminem song, having worked security for the fellow Detroit native, but couldn't get permission from the rap artist in time to use one on Saturday.

Atlantic City lightweight Osnel Charles (9-4-1, 1 KO) will try to snap a three-fight winless streak on Dec. 22 at Sands Casino Resort in Bethlehem, Pa. Charles is fighting unbeaten Naim Nelson (8-0, 1 KO), of Philadelphia, in an eight-rounder.

Boxing returns to Atlantic City on Feb. 23, 2013 at Bally's Atlantic City. Wildwood light-heavyweight Chuck Mussachio (18-2-2, 5 KOs) and Atlantic City light-heavyweight Lavarn Harvell (12-0, 7 KOs) are scheduled to be on the card. Bethlehem, Pa. welterweight Ronald Cruz (17-1, 12 KOs) will headline Philadelphia promoter Russell Peltz's show.

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