The chief executive behind Microsoft’s planned $75bn acquisition of Activision made a last-ditch attempt to save the deal in a San Francisco courtroom on Wednesday, in the face of a US government objections that could result in its annulment as early as next week.

The acquisition of the gaming company would almost certainly collapse if the judge sided with the Federal Trade Commission, according to executives and lawyers for the companies at the hearing in federal court, which began last Thursday. The agency is seeking a preliminary injunction to stop the deal closing while it pursues a parallel case in an administrative court.

However, evidence and questioning during the hearing have lifted the hopes of the deal’s supporters on Wall Street. Judge Jacqueline Scott Corley repeatedly prodded an expert witness called by the FTC over his analysis of the deal and at one point cut off the agency’s lawyer during questioning. She also invited a Microsoft executive to swear under oath that the company would grant Sony’s PlayStation a 10-year licence for Activision’s most popular game, Call of Duty — a central issue in the case.