It looks like Amy Winehouse has fallen off the wagon -- again.

The Sun is reporting that a bedraggled Winehouse was seen downing a miniature bottle of vodka at the liquor counter of a shop in London on Thursday morning, just before checking in for treatment at a rehab center.

An eyewitness recalled the troubled singer's condition in the store. "She seemed out of it. She was stumbling about, slurring her words."

The person continued, "I was shocked to see her buy vodka so early in the day, and even more shocked to see her knock it straight back."