Fighting past the ninth round for the first time, Davis (23-0, 22 KOs) showed why his nickname is Tank, releasing a barrage of punches in the final round before a left uppercut to the head ended the fight at the 1:44 mark when referee Jack Reiss called it.

Davis, becoming a two-division champion in his adopted hometown, dropped Gamboa three times. He landed a left hand to knock the veteran down in the final seconds of the eighth, bringing fans in the lower bowl at sold-out State Farm arena to their feet.

But Davis, 25, entering his prime and moving up to lightweight for the first time, couldn't finish off the 38-year-old Gamboa until the end. Gamboa took a beating in the fifth from Davis' left uppercuts but had plenty of punch resistance.

Davis had a big lead on the cards at the time of the stoppage, with judges giving Gamboa only the seventh round.

Reiss called a brief timeout before the start of the third when Gamboa complained about an issue with his right shoe. His corner retied the shoe before the start of the fourth and taped it heavily before the start of the fifth.

Davis, a southpaw, won Atlanta's first world championship fight since Evander Holyfield successfully defended his heavyweight belts against Vaughn Bean 21 years ago.

His next fight is undecided. Super lightweight champion Vasyl Lomachenko of Ukraine said in April that he wants a match, and Davis said last month that he's ready, too. But a more likely possibility is Davis returning to featherweight to face Mexico's Leo Santa Cruz.

Australian Associated Press