Timothy Bradley's fists and head-butts got the best of Devon Alexander.

Bradley defended his WBO 140-pound title and took Alexander's WBC belt, winning a unanimous technical decision after the fight was stopped in the 10th round Saturday night at the Silverdome.

"I'm ruthless," said Bradley, refusing to apologize for leading with his head. "I'm reckless."

The ringside doctor ruled Alexander couldn't keep his left eye open and halted the fight at 1:59 of the 10th after an accidental head-butt.

"I couldn't see, so they had to stop the fight," Alexander said.

Bradley (27-0) handed Alexander (21-1) his first loss in the biggest fight for each rising star.

"If that's the best in the world, that's weak," Bradley said.

Both fighters took a risk by taking a bout either could lose, but the payoff could be huge.

The 27-year-old Bradley took a step toward a possible fight with Manny Pacquiao or Floyd Mayweather Jr. down the road, but WBA super lightweight champion Amir Khan could be his next opponent.

"I would love a chance with Floyd Mayweather," Bradley said. "I think I've got to take Amir Khan out next, then there will be no doubt who the best 140-pounder is in the world."

Bradley's camp said earlier in the week that it would welcome a fight with Khan, if the time was not right for a bout with Mayweather or Pacquiao.

"Khan is probably No. 1 on the list," Bradley said. "The key name on the list down the road is Manny Pacquiao."

HBO, though, has a rematch clause in the contract to put Bradley, of North Palm Springs, Calif., back in the ring with the 23-year-old St. Louis southpaw.

"I want a rematch with Timmy Bradley," Alexander said.

HBO executive Kery Davis isn't sure the cable network will exercise its option.

"We haven't made a decision," he said.

In a fight that had to be tough to score with each fighter throwing flurries of punches, the judges all had Bradley ahead in the bout — 97-93, 96-95 and 98-93 — when it was suddenly halted because Alexander's left eye was burning so much he couldn't open it.

Alexander needed four stitches to close a gash between his right eye and eyebrow and two to the side of his left eye.

"He wasn't hitting me clean," Alexander said. "I thought I was ahead in the fight."

Dr. Peter Samet said he asked Alexander to open his left eye three times and he couldn't do it.

"I feared temporary nerve damage, so I recommended to stop the fight," Samet said.

The beginning that led to the end for Bradley came in the third round when Bradley seemed to land a blow on Alexander's right eye with a wicked combination of a thumb and head-butt.

The crowd was quiet when referee Frank Garza got between the fighters in the 10th after another head-butt — ruled accidental by Garza — sending Alexander to a corner to take a look at his eye before deferring to a ringside doctor in another corner.

"I did not want the fight to end that way," Bradley said. "I really wanted to finish the fight."

The fans did, too, and they made their displeasure known with a chorus of boos.

Alexander's trainer, Kevin Cunningham, was disappointed Garza didn't listen to his warnings.

"I told the referee that Bradley's last six opponents had been cut by head-butts," Cunningham recalled.

Garza, though, insisted the one in the 10th was accidental.

"It was a completely different head-butt than the previous one in the fight," Garza said. "I stopped the fight after consultation with the ringside physician."

The former home of the Detroit Lions and Pistons was configured to put the ring in a corner of an end zone, putting curtains up to create a relatively intimate venue with 9,000 seats on the floor and lower bowl. About half those seats seemed to be filled, but the announced attendance was 6,247.

Members of the military, police officers, firefighters, emergency medical service personnel and military veterans were admitted free if they showed up in uniform by the Silverdome's new owners, who are trying to make the venue viable.

The Toronto-based company that paid $583,000 for the 80,300-seat stadium in 2009 — after it was largely idle for seven years — gave promoters about as much money to land the big-time fight.

"The site was worthy for this site," said Gary Shaw, who co-promoted with Don King.