Detroit Lions' Nate Burleson 911 -- Witness: I'd Guess He's Drunk

Moments after Nate Burleson smashed his SUV into a median -- a witness called 911 and said, "He was losing his balance" ... and that he believed the Detroit Lions star appeared to be intoxicated.

Burleson wrecked last Monday night, and police have said they do not believe alcohol or drugs were a factor -- but on this 911 tape you clearly hear the caller say, "He looks a little messed up. He's walking around, but if I had my guess I'd say he's drunk."

Nate told police he lost control while reaching for a pizza box that was falling off his front seat.

TMZ spoke to a witness at the pub and pizza spot where Burleson had been hanging out that night who told us he had a couple of beers.