Google opened its defense against allegations that it holds an illegal monopoly on online advertising technology Friday with witness testimony saying the industry is vastly more complex and competitive than portrayed by the federal government.

As the government wraps up its case, it has built a picture of how Google has become dominant among companies that buy and sell ads online.

Lawyers for the government have revealed damning Google correspondence and called witnesses who describe anti-competitive practices. Google, however, says ‘there is no monopoly power.’