Spinks won all 12 rounds on two judges' scorecards

Dawson dominated the opening rounds and recovered from a knockdown in the 10th to win 116-110 117-109 118-108.

Julio Diaz claimed the IBF lightweight title as champion Jesus Chavez retired in round three with a knee injury.

And ex-welterweight king Cory Spinks defended his IBF light middleweight title, outpointing Rodney Jones.

Dawson's left-handed style and superior reach were too much for Poland's Adamek during much of their bruising fight at the Silver Spurs Arena and he improved his record to 23-0.

"This was a long time coming and I finally reached my potential in this fight," said the 24-year-old.

"He caught me with a good punch in the 10th but he didn't hurt me. I got back up and went back to the game plan."

Diaz (34-3) was credited with his 25th knockout when fellow Mexican Chavez collapsed 22 seconds into the third round trying to dodge a punch.

"It felt a little weird when my knee went out," Chavez, 34, said. "This was my good leg. I wear the brace just for support."

Meanwhile, Spinks (36-3) won nine rounds on one judge's card and all 12 on the other two as he defended his light middleweight title.

"He's a long, rangy guy so I had to outsmart him," said the 28-year-old son of former heavyweight champion Leon Spinks.