Microsoft's put its two-penn'orth in to the European Commission's anti-trust investigation of Google, and has filed a formal complaint.
It says that Google's dominance of the search market - EC figures put its market share at 95 percent - works 'to the detriment of European consumers'.
"We’re concerned by a broadening pattern of conduct aimed at stopping anyone else from creating a competitive alternative," says Microsoft's senior vice president and general counsel, Brad Smith.
The EU is currently investigating whether Google has violated anti-trust laws, after complaints from several organizations including Microsoft shopping site Ciao.
Microsoft is particularly annoyed that Google bars competing search engines from properly accessing YouTube, and that - unlike Android or the iPhone - nor can Microsoft's Windows Phones.
"As a result, Microsoft’s YouTube 'app' on Windows Phones is basically just a browser displaying YouTube’s mobile Web site, without the rich functionality offered on competing phones," says Smith.
It also complains that Google is trying to block access to content owned by book publishers. While a US federal court last week rejected Google's plans to prevent competitors from searching orphan books, there's currently no similar prohibition in Europe.
And Microsoft objects to the way Google prevents its advertisers from using their data in an interoperable way with other search advertising platforms, such as adCenter; and the way it contractually blocks leading Web sites in Europe from distributing competing search boxes.
Of course, Microsoft has had its own run-ins with the EU over anti-competitive practices, something which Smith acknowledges.
"There of course will be some who will point out the irony in today’s filing," he says. "Having spent more than a decade wearing the shoe on the other foot with the European Commission, the filing of a formal antitrust complaint is not something we take lightly. This is the first time Microsoft Corporation has ever taken this step."