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Yahoo! Inc. (Nasdaq: YHOO), the beleagured No. 2 search engine, is expected to have flat revenue and earnings in the first quarter as it seeks to turn around stagnant advertising and search divisions under its new CEO. Yahoo

Yahoo CEO Scott Thompson has led the company toward “formal action” against Facebook over alleged patent infringements.

It's been alluded to for weeks, but now it's official: Yahoo CEO Scott Thompson has led the company to formal action against Facebook over alleged patent infringements.

All Things D broke the story moments ago.

Here's what Yahoo told the popular tech blog:

Yahoo! has invested substantial resources in research and development through the years, which has resulted in numerous patented inventions of technology that other companies have licensed. These technologies are the foundation of our business that engages over 700 million monthly unique visitors and represent the spirit of innovation upon which Yahoo! is built. Unfortunately, the matter with Facebook remains unresolved and we are compelled to seek redress in federal court. We are confident that we will prevail.

Facebook has commented on the patent lawsuit. Here's what the world's largest social network told All Things D: We're disappointed that Yahoo's effort to engage with us was limited to a few short phone calls and that we continue to learn of new developments about a long-time partner through the press. We will defend ourselves vigorously against these puzzling actions.

The lawsuit comes roughly two months after Scott Thompson, Yahoo's new CEO, took the over the reigns of the company. It's been reported that Thompson is known especially for his aggressive approach to correcting the path of the internet giant he's now at the helm of.

About one week ago, Yahoo announced it would begin a major restructing of its operations, which is likely to include thousands of layoffs. The restructuring will involve Yahoo's products division as well as areas in which the company has struggled. Thompson, a former eBay Inc. executive, said in January that Yahoo would focus on its strengths and priortize how it uses its capital.

The patent infringement measures taken against Facebook are just the next order of business for Thompson. Mashable reports that Yahoo notified Facebook of the then-pending lawsuits at the same time it informed the New York Times. Many see the actions against Facebook as a desperate attempt by the company to recapture its relevancy, even Digital Trends, which is, incidentally, a Yahoo contributor.

We'll keep you posted as the story unfolds.

For now, here's the official complaint for patent infringement:

Software Yahoo Facebook Patent