Different day, different rehabilitation clinic, same outcome: Britney Spears reportedly left Promises, a Malibu, Calif., facility after less than a day.

"It was against their advice," a source told People magazine. "If she comes back for treatment, Promises will have to assess the situation. Sometimes people come back, but it doesn't look good."

Promises is not a locked-down facility, so patients are able to leave the program if they want.

It was Spears' second rehab attempt within a week, E! News said. The pop star last week entered Eric Clapton's Crossroads Center in Antigua, but checked out a day later.