Facebook Inc. has signaled it’s ready for a patent battle.

Yahoo Inc. sued the social-networking site in March for patent infringement, and lawyers for Facebook fired back Tuesday with an answer and counterclaims. Facebook claims Yahoo is infringing 10 patents covering services such as its homepage, content optimization, relevance engine, Flickr photo-sharing service and advertisements displayed throughout the site.

“From the outset, we said we would defend ourselves vigorously against Yahoo’s lawsuit, and today we filed our answer as well as counter-claims against Yahoo for infringing ten of Facebook’s patents,” Facebook general counsel Theodore Ullyot said in an e-mailed statement. “While we are asserting patent claims of our own, we do so in response to Yahoo’s short-sighted decision to attack one of its partners and prioritize litigation over innovation.”

Three of the patents Facebook asserts in this suit were invented by its own engineers, and one related to tagging digital media was co-invented by Mark Zuckerberg. The others were acquired from New York University, IPG Electronics and RightPoint, one as recently as Friday.

It would have made sense for Facebook to settle the Yahoo suit quickly before it goes public, said Eric Goldman, an associate professor at Santa Clara University School of Law and director of the High Tech Law Institute. But Facebook has chosen a different route, one that could give it some additional leverage in settlement negotiations.

“Facebook has signaled that it’s digging in and is ready to fight tooth and nail,” Goldman said. “You don’t get the great settlement deals if you just capitulate early.”

Facebook hasn’t been quick to settle patent infringement claims in the past. In 2008, Leader Technologies Inc. sued Facebook, alleging the company infringes a patent on its data management tool. The case went to trial in Delaware district court in 2010, the first time Facebook had ever faced a jury.

The jury found Facebook had infringed the patent, but it also invalidated the patent because Leader had sold the technology before seeking patent protection. Leader appealed the ruling to the U.S. Court of Appeals for the Federal Circuit, which heard oral arguments in March. The court has not yet issued an opinion.

Facebook was represented at the Delaware trial by a Cooley team that included litigation chair Michael Rhodes along with partners Heidi Keefe and Mark Weinstein. That same team, with the addition of firm chair Stephen Neal, is also representing Facebook in the Yahoo case, along with William Lee and Cynthia Vreeland of Wilmer Cutler Pickering Hale and Dorr.

And they’re up against Quinn Emanuel Urquhart & Sullivan’s Charles Verhoeven and his team of litigators, who have led Google Inc. to victory in several patent infringement trials.

This story originally appeared in American Lawyer sibling publication The Recorder.