Mosley (right) produced a polished performance

Mosley boxed intelligently as he continued to work on the swelling to Vargas's left eye, forcing the referee to intervene.

The swelling started to appear in the second round, but Vargas battled on bravely despite the problem.

But the damage was done, and Mosley secured his 42nd professional victory.

"As the rounds went on, the swelling got bigger and bigger, and I thought 'Wow, look what we have here'," said Mosley.

Vargas suffered terrible swelling to his eye

"He tried to push me and shove me, and I was trying to keep myself away because he was so heavy. That fight showed that I'm a very strong welterweight."

Mosley, 34, has said this would be his last fight at light middleweight before returning to welterweight, but Vargas, who said the swelling was caused by a headbutt, wants a rematch.

"I was wondering why they stopped the fight," said Vargas.

"I was the one pushing the action, backing him into the ropes. I definitely want a rematch. Let's see what he says."

Meanwhile, Mark "Too Sharp" Johnson was stopped by WBO bantamweight champion Johnny Gonzalez in the eighth round.

The bout was a 12-round non-title fight after Johnson failed to make the weight.