A pending U.S Federal Trade Commission (FTC) lawsuit aimed at blocking Microsoft's $69 billion buyout of Activision Blizzard only came about because it was worried that its European counterpart intended to strike a deal over the merger.

That's according to a new report which says that the 8 December lawsuit was filed just hours after a phone call between the U.S. and European antitrust watchdogs in which it became clear that EU officials planned to begin talks with Microsoft. Both parties are concerned that a buyout could give Microsoft's Xbox an unfair advantage over the competing PlayStation and Nintendo platforms.

A Bloomberg report, citing insiders "familiar with the investigations," claims that the FTC was concerned that any move by its European counterpart would undermine its own stance if it sued too late. As a result, the lawsuit was filed the same day the two watchdogs spoke on the phone.

Officials from the EU aren't expected to decide whether Microsoft's buyout of Activision Blizzard can go through until April, with the FTC previously expected to hang fire until it could help broker a global resolution. But the call between the FTC and the European Commission changed all of that.

"The EU officials indicated on the call they intended to begin talks with Microsoft about potential remedies," Bloomberg reports. "That prompted the FTC to file its case the same day to send a strong signal to EU Competition Commissioner Margrethe Vestager and her staff, the people said, even though technically the commission wouldn’t entertain remedy proposals from the companies until later in the process."

For its part, Microsoft is adamant that there is no antitrust case to answer. Much of the talk has been about Microsoft potentially blocking some Activision Blizzard games from releasing on competing platforms, but the company says that isn't going to happen. What's more, it's willing to sign a 10-year deal to ensure that Call of Duty remains cross-platform - launching on both Nintendo Switch and PlayStation throughout.