Denies DUI Drug Allegations

Sobriety Test Showed I Was Fine

Surf legend Bruce Irons tells TMZ Sports he's confident he will beat the DUI Drug allegations against him -- claiming the field sobriety showed he was "fine."

As we previously reported, the 39-year-old surfer was arrested in Newport Beach last week when cops claim they found him passed out behind the wheel of a car with the engine running.

He was booked for driving under the influence of a controlled substance and possession of a controlled substance without a prescription.

Now, Irons tells us ... he's confident he'll be cleared -- and called the whole thing a "hiccup in the road."

"I did the sobriety test and I was fine," Irons told us at LAX on his way back to…