Boxing Champ Julio Cesar Chavez Jr. Arrested for DUI

Middleweight boxing champ Julio Cesar Chavez Jr. -- son of the legendary Julio Cesar Chavez -- has been arrested for DUI, TMZ has learned.

Law enforcement sources tell TMZ, Julio was pulled over in his black Land Rover for a routine traffic stop last weekend on an L.A. freeway -- and when officers approached the vehicle, they detected a strong odor of alcohol.

The officers administered several field sobriety tests -- and we're told Julio's reflexes weren't quit up to par, so they placed him under arrest.