LAS VEGAS: World Boxing Council champion Floyd Mayweather extended his perfect record to 44 victories Saturday, beating Robert Guerrero by unanimous decision in their welterweight title fight.

Mayweather, who was defending his title for the first time since serving close to three months in jail last year after being convicted of domestic violence, dominated a bloodied Guerrero for the majority of the fight at the MGM Grand Hotel and Casino.

All three judges scored the 12-round fight 117-111 in favour of Mayweather.

In his first fight in a year, the 36-year-old Mayweather also snapped Guerrero's 15-fight win streak dating back to 2005. While Mayweather improved to 44-0 with 26 knockouts, Guerrero fell to 31-2-1 with 18 wins inside the distance.

The fight started slowly, with Guerrero the aggressor and Mayweather feeling the challenger out.

Mayweather began to seize control in the third round and dictated the pace from there, using his superior foot and hand speed to keep Guerrero off balance.

Mayweather landed one of his hardest punches in the eighth round – a roundhouse right that wobbled Guerrero, whose face was starting to show the effects of being hit with a barrage of straight rights, stinging counterpunches and lunging jabs.

The champion also opened up a cut near Guerrero's eye in the eighth.

The ring savvy Mayweather cruised through the middle and later rounds, using his strong defence to slip punches on the ropes and in the centre of the ring.

Mayweather was so dominant in the later rounds that he stopped moving from side to side in the 11th, choosing to slug it out and landing punches at will against Guerrero, who never gave up but was hopelessly overmatched.

The only blemish on his performance was that Mayweather, who made $32 million for this fight, failed to get the knockout.

On the undercard, former Mexican Olympian Abner Mares captured the WBC featherweight world title with a ninth round technical knockout of Daniel Ponce de Leon.

The 27-year-old Mares remained undefeated as he knocked the champion down in the second round and then again in the ninth.

He sent de Leon to the canvas early in the ninth with a thundering right hand before referee Jay Nady halted the fight later in the round with de Leon pinned on the ropes and absorbing some heavy blows from Mares.