American Floyd Mayweather has retained his World Boxing Council lightweight title with a unanimous 12-round decision over Mexico's Jose Luis Castillo.

Two of the three ringside judges in Las Vegas saw it 115-113 for Mayweather while the third gave it to the champion 116-113.

Mayweather remains undefeated in 29 fights, with 20 victories inside the distance, while Castillo fell to 46-6-1.

"Jose Luis Castillo was a tough opponent and he gave me a great fight, but I showed that I am the best pound-for-pound fighter," said Mayweather, who beat Castillo on points in their first fight.