Serena Williams attends the Burberry Body Launch event at Burberry on Oct. 26, 2011 in Beverly Hills

*TMZ is reporting that Serena Williams escaped to a panic room inside of her L.A. mansion after security cameras picked up a suspected intruder … but it was all a case of mistaken identity.

According to the website, Serena’s assistant called 911 around 6 a.m. last Wednesday claiming a possible burglar or prowler was on the premises.  Serena was so afraid that she retreated to her panic room.

But in the end, it was a false alarm. According to TMZ, the person on Serena’s security camera was a random drug tester for an unspecified tennis association, stopping by Serena’s home unannounced for to collect a sample.

Police rushed to the scene after the 911 call, but quickly figured out the mistake.