EXCLUSIVE

Oscar De La Hoya was arrested for DUI in Pasadena, CA Tuesday night ... TMZ Sports has learned.

Law enforcement sources tell us the 43-year-old was pulled over for speeding in a Land Rover around 2 AM and during the stop, officers suspected he was drunk.

We're told Oscar bombed a series of field sobriety tests and was arrested for DUI. He was cited and released to his manager.

Earlier in the evening, Oscar was seen at multiple bars in the area, including Barney's Beanery in Old Town Pasadena where he posed for a pic with a fan.

Oscar has struggled with substance abuse for years -- and has been to rehab for alcohol and drug issues in the past.