Anheuser-Busch's (NYSE:BUD) position as the leading brewer in the U.S. may be safe, but its reign as the global leader may not be.

On Monday, Belgium's Interbrew -- distributor of Labatt Blue, Rolling Rock, and Beck's -- and Brazil's AmBev confirmed that they are in discussions that may lead to a "significant transaction." Clearly, a merger between the world's fourth- and fifth-largest brewers, creating the world's largest brewer, would qualify.

Anheuser-Busch currently holds that No. 1 title. The company controls half of the U.S. domestic market, a share far greater than both Altria Group's (NYSE:MO) part-owned Miller and Coors (NYSE:RKY). In addition to Budweiser and Bud Light, the two global bestsellers, Anheuser-Busch owns large stakes in Tsingtao in China and Grupo Modelo in Mexico, the leading brewers in those countries.

So, wouldn't that make Anheuser-Busch a natural suitor for AmBev? You bet.

Despite having lost market share, AmBev accounted for 63.2% of the Brazilian beer market -- the world's fourth largest -- in the fourth quarter. Hypothetically, buying AmBev would expand Anheuser-Busch's reach nicely into South America. And while that reach is precisely why some see Interbrew and AmBev as a potential fit, Anheuser-Busch's ability to pay cash would be attractive to AmBev's shareholders.

Of course, it's possible that Interbrew and AmBev aren't talking mergers at all. According to Reuters, "Other possible scenarios from the Interbrew-Ambev talks include a deal over Interbrew's stake in a Mexican brewer or even a distribution agreement." That might involve AmBev taking Interbrew's stake in Mexican brewer Femsa in exchange for AmBev shares.

That said, if it turns out AmBev is for sale, don't be shocked if Anheuser-Busch makes a play.

Give us your take on the Anheuser-Busch discussion board.

Fool contributor Jeff Hwang owns shares of Anheuser-Busch.