Lindsay Lohan back on the booze ... and fighting

Friends fear Lindsay Lohan's sobriety has gone out the window after she attacked Girls Gone Wild creator Joe Francis at Miami nightclub Mokai reports NW Magazine.

Sources say Lindsay became agitated with Joe when she thought he was acting like a sleaze towards other women. She went over to Joe and started hitting him despite the fact they'd been hanging out together.

"Lindsay gave him a piece of her mind - they had to be physically pulled apart," says an eyewitness.

She then bolted before police could be called and went to another Miami nightspot, Prive. Once inside, she was back to her party-hard ways, dancing until 5am. While reps for the actress claim she drank nothing but Red Bull and water, insiders say her behavior hints she's back on the booze.

"Lindsay's been drinking and partying heavily," says a pal. "She is not doing so well with sobriety."

Insiders say she no longer takes Alcoholics Anonymous seriously and hasn't been to a meeting for weeks.