The young American champion Chad Dawson controversially beat Jamaican veteran Glen Johnson on points to retain his World Boxing Council (WBC) light heavyweight title on Saturday night.

Dawson was almost floored in rounds three and 10 and the 39-year-old Johnson was stronger toward the end but the judges Nicolas Hidalgo, Peter Trematerra and Jack Woodburn all scored the bout 116-112 for the unbeaten Dawson.

The decision was jeered by the crowd at St Pete Times Forum and left Johnson furious.

"I fought my heart out. I can't believe at my age, at 39, they still rip me off like this," said Johnson, who has a long history of losing controversial fights.

With the victory, Dawson improved his ring record to 26-0 with 17 knockouts and Johnson slid to 47 wins (32 knockouts) against 12 losses and two draws.

Throughout the bout, Johnson used aggression and effective power punching to pressure the 25-year-old champion.

Dawson exhibited good boxing skills, landing and moving in angles to earn the verdict of the judges.

The action-packed bout featured several exchanges of head and body combinations.

Johnson was more effective when the action was close and although Dawson rallied well in the middle rounds, Johnson stepped up the pressure in the final four rounds, especially in the 10th, when he rocked Dawson with a right to the head.

Johnson followed with additional shots to the head.

Dawson struggled to stay on his feet and barely survived the attack.

Over the last two rounds, Dawson came back admirably but Johnson continued to be the aggressor and connected with several strong rights to the head.

Judges Hidalgo (Venezuela), Trematerra (USA) and Woodburn (Canada) all scored the first 10 rounds of the disputed bout identically, giving Dawson a 7-3 edge in rounds.

Hidalgo gave Johnson round 11 and Dawson round 12, while Trematerra and Jack Woodburn gave Dawson the 11th and Johnson the 12th for a 116-112 verdict across the board.

"He's a good fighter but he's not good enough to beat me - Of course I want a rematch," Johnson told reporters after the bout.

Dawson felt satisfied with the judges' ruling but acknowledged Johnson's worth.

"It was definitely the toughest fight of my career, but I executed my game plan, and put rounds in the bank," he said.

"I'm looking to fight the best. Glen Johnson was one of the best. I took care of business and now it's time to move on," Dawson added.