One week after Lindsay Lohan admitted to relapsing with a 'cup of wine' in an episode of her OWN docu-series "Lindsay," sources claim the recovering actress has lapsed once again.

Lohan flew to California on Friday to attend the famously drug- and alcohol-infused music festival, Coachella. At the time, it was reported that she promised friends she'd stay sober during her time at the three-day event, but sources tell In Touch magazine that wasn't the case.

The former "Means Girls" star was reportedly seen holding a glass of "clear liquid" -- believed to be vodka -- as she hung out backstage with her sister Ali Lohan during Kid Cudi's performance.

"She looked completely out of it. She couldn't stand up straight and she was frantically chain smoking cigarettes," an eyewitness said. "In one of her hands she had a plastic cup with a clear liquid in it."

The insider added that one of the people in Lohan's group eventually went to the bar and ordered four vodkas.

"He handed one to Lindsay and she started drinking it. She didn't seem to care who saw and none of the group seemed concerned," the source said.

Lohan ended her sixth rehab stint in August 2013. Given the revelations made during the April 13 episode of "Lindsay," it is unclear how long she's been sober.

"Of course it's jarring when you relapse and you try to stay sober," she said on the show after her confession. "It's a scary thing."