In fact, according to The New York Times, Mayer and her team have already started testing Google search ads in a small number of desktop and mobile queries. It was first discovered by SEOBook's Aaron Wall, who alternately saw Yahoo results with Bing ads and ones with Google ads when he used different browsers. Both of them have confirmed the arrangement to NYT but wouldn't discuss the partnership in detail. "As we work to create the absolute best experiences for Yahoo users, from time to time, we run small tests with a variety of partners including search providers," was all the company said.

Yahoo and Microsoft revised their 10-year partnership in April: Bing used to provide Yahoo's search results and ads exclusively. Now, the former has the right to enlist the help of other providers for up to 49 percent of its search results. The two could completely break up by October, as well, though it's clear Yahoo's still testing the waters before deciding.