Lindsay Lohan's week is off to a rough start.

Following a weekend full of reports -- and her own admission -- that she had failed court-mandated drug tests, a California judge has issued a warrant for her arrest, TMZ reports.

Superior Court Judge Elden Fox issued the bench warrant in Beverly Hills, but Lohan will remain free pending a Friday court hearing, according to officials from Los Angeles County Superior Court.

The bench warrant is on hold until Friday at 8:30 AM, when Lindsay is ordered to appear in court.

Lohan, 24, could be sentenced to 30 days behind bars for each of the two failed tests.

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“I predict she will get at least 30-45 days for the violations,” Santa Monica-based criminal defense attorney Steve Cron told “Judge Fox is going to want to ensure Lindsay is taking the court system seriously and right now, she just doesn’t seem to get it.”

Lohan tested positive for cocaine and amphetamines, TMZ reports.

Lohan spent two weeks in jail this year after violating probation stemming from convictions involving her 2007 arrests for drug use and driving under the influence. She spent another 23 days undergoing rehabilitation at Ronald Reagan UCLA Medical Center.

Fox had threatened her with 30 days in jail for each probation violation. Fox must now decide whether to send her back to jail or back into treatment.

Lohan posted a series of Twitter messages last Friday acknowledging her drug problem.

"Regrettably, I did in fact fail my most recent drug test," she tweeted.

She also said, "substance abuse is a disease, which unfortunately doesn't go away over night. I am working hard to overcome it."

Lohan often posts updates with the account that's verified by Twitter as belonging to the actress.

The Associated Press contributed to this report.

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