Getty

It's still not entirely clear if Paul Pierce had alcohol in his system during his arrest last week ... as TMZ Sports has learned cops are still waiting on his blood test results.

The NBA legend, as you know , was taken into custody by the California Highway Patrol on Oct. 7 ... after authorities say they found him asleep at the wheel of his Range Rover SUV while on Highway 101 in Los Angeles. Getty

Officers claimed Pierce exhibited signs of alcohol impairment -- and he was ultimately arrested on suspicion of DUI.

On Monday, a spokesperson for the CHP told us they haven't yet gotten results that establish Pierce's BAC during the incident.

The rep added "a local crime lab" is responsible for processing the sample, and a timeline for the return of the results is not kn

See Full Page