In a bid to temporarily block Microsoft’s $69 billion planned acquisition of Activision Blizzard that could revolutionize the gaming industry, the US Federal Trade Commission (FTC) sought a five-day hearing.

The hearing, which began on June 22 and will conclude on June 29, is one of Microsoft’s most important trials.

As witnesses, Microsoft CEO Satya Nadella and Activision Blizzard CEO Bobby Kotick will appear in court in person. A video deposition will also be conducted by Jim Ryan, head of Sony’s PlayStation division.

Sony has opposed the deal for months, claiming that if Microsoft acquires Activision Blizzard, Call of Duty may become console-exclusive. A $3 billion break-up fee will be imposed on Microsoft if the Microsoft-Activision deal fails to close on July 18.