The U.S. government is taking aim at what has been an indomitable empire: Google’s ubiquitous search engine that has become the internet’s main gateway.

The legal attack will swing into full force Tuesday in a Washington D.C. federal courtroom that will serve as the battleground for the biggest U.S. antitrust trial since regulators went after Microsoft and its dominance of personal computer software a quarter century ago.

The 10-week trial before U.S. District Judge Amit Mehta is expected to include potentially revelatory testimony from top executives at Google and its corporate parent Alphabet, as well as other powerful technology companies. Alphabet CEO Sundar Pichai, who succeeded Google co-founder Larry Page in 2019, will be among the most prominent witnesses likely to testify. Court documents also indicate one of Apple’s highest-ranking executives, Eddy Cue, might be called to the stand.

The case against Google mirrors the one brought against Microsoft in many ways, including the existential threat it poses to a renowned tech giant whose products are relied on by billions of people.