Potrero Hill-based Zynga is announcing today a partnership with international popstar Enrique Iglesias that will kick off next week in its most popular game, CityVille.

Under the deal, which starts next Tuesday and runs for seven days, players will be able to build “Euphoria Arenas" for their virtual cities, collect some free branded virtual items, preview a video of his single, “I Like How It Feels,” and interact with the singer’s avatar.

The partnership comes just as Iglesias has kicked off an international concert tour, which is branded “Euphoria.” This is the third celebrity event for the large social game company, following one with Lady Gaga in May and Dr. Dre last December.

“Enrique has a very broad international reach, and since we are trying to build the largest player base possible, this is a perfect partnership for us,” said Scott Koenigsberg, CityVille’s director of business strategy. “After the seven-day event, players can keep the arenas and items in their cities.”

In the game, 72 million players collaborate with others to build “the city of their dreams,” complete with houses, parks, governments, baseball stadiums, and so forth.

CityVille is one of five Zynga games that reportedly occupy all five top positions among games on Facebook. (The other four are Empires & Allies, Texas HideEm Poker, FarmVille, and Adventure World.)

As of July, the company said it had 232 million active monthly users over the giant social network platform in different 166 countries. Accordingly, when it filed with the SEC for its upcoming IPO on July 1, Zynga listed on its S-1 Form under Risk Factors, “if we are unable to maintain a good relationship with Facebook, our business will suffer.”

The company makes money from the relatively small number of users who purchase virtual goods that enhance their gaming experience, but it has scaled so rapidly over its first four years of operation that the company is solidly profitable.

In its most recent quarter, however, profits fell dramatically – by 95 percent, from $27.2 million in the quarter ending March to $1.3 million for the quarter ending in June.

One probably factor in this decline is Facebook's new requirement that all game developers use its Facebook Credits payment system, which takes a 30 percent cut of revenue on the sales of all those virtual goods.

Still, the company, which founder Mark Pincus named after his late bulldog  Zinga, is projected to raise $1 billion when it goes public.

The company’s users also generate significant philanthropic contributions, especially after natural disasters, raising more than $6 million for various international nonprofit organizations since 2009.