Google and Yahoo prefaced their two-week test of Google’s AdSense for Search in Yahoo’s search results by chatting with antitrust regulators at the Justice Department.

Suspecting Microsoft and possibly other concerned parties would complain, it appears Yahoo and Google acted to allay potential federal worries about their trial of Google ads in Yahoo search. Microsoft did make its position known, releasing a statement opposing a tie-up that in their opinion put 90 percent of search advertising in one place.

A Retuers report cited statements from Google and Yahoo on their approach to heading off possible interference:

“We informed the Justice Department before we launched this test and we have been responsive to their questions about it,” Google spokesman Adam Kovacevich said.

Yahoo said separately that it also spoke to antitrust regulators. “Yahoo proactively kept the Department of Justice informed of its intentions to conduct this limited test with Google and have provided information to DOJ on the nature of the test,” Yahoo spokeswoman Tracy Schmaler said.

Any Microsoft opposition would come from the point of view of a very experienced company when it comes to antitrust issues. Microsoft has been under the supervision of a federal court for years as a result of an old antitrust suit filed by numerous states and the Justice Department.