Facebook is suing a German website which it believes has copied its look and feel.
The intellectual property lawsuit states that Facebook's reputation could be damaged by invalid associations with studiVZ, and accuses the site of "copying the look, feel, features and services".
StudiVZ claims around 10 million users. The site was launched in October 2005 by two Berlin students and is owned by German publishing firm Verlagsgruppe Georg von Holtzbrinck.
The lawsuit was filed on 18 July in a California federal court, and seeks monetary compensation in an amount to be determined at trial.
StudiVZ responded on the same day by seeking a declaratory judgment at the District Court in Stuttgart that Facebook's claims are without merit.
StudiVZ reckons that Facebook is just angry because it has not seen the same success in Germany as it has in the UK, US and other countries.
"Their strategy appears to be: 'If you can't beat them, sue them,'" said Marcus Riecke, chief executive of studiVZ.
Facebook has itself been the victim of internal lawsuits following accusations that found Mark Zuckerberg stole the concept of the site from ConnectU, a service run by fellow Harvard students.
Allen died from complications of non-Hodgkin's lymphoma
Stanford researchers made the discovery via data from Greenland
Created via a thin, flexible, and transparent hierarchical nanocomposite film
Rolls Royce will use AI powered by Intel's Xeon Gold processors and SSDs for memory