For more than a year, Anheuser-Busch InBev has endured an increasingly strained relationship with its Mexican partner, Corona brewer Grupo Modelo. But with rivals exploring opportunities to join forces south of the border, A-B and Modelo could be pressured to get closer than ever before.

Femsa SAB, Mexico’s second-largest brewer behind Modelo, is holding merger talks with several companies. Its beer operations are officially on the table, but analysts expect all of Femsa—which is also Mexico’s largest Coca-Cola bottler and the owner of the Oxxo convenience-store chain—could ultimately be sold as a single package. Initial estimates value the company at about $9 billion.

Analysts say a merger between Anheuser-Busch-Modelo and Femsa would almost certainly face Mexican antitrust opposition. So observers have generally concluded that SABMiller, the London-based beer giant that owns Miller Brewing among other brands, is the most likely suitor.

Coca-Cola also has the resources to purchase Femsa, though it would have to decide whether it is comfortable moving beyond soft drinks into alcoholic beverages. Heineken, which is already a minority partner of Femsa’s Kaiser brewery in Brazil, might be able to afford just the beer component of the company, but it is already burdened with debt from its recent acquisition of the United Kingdom’s Scottish & Newcastle.

Femsa’s merger with a global partner would likely make the brewery more competitive in Mexico and beyond. And another example of industry consolidation could finally convince Modelo shareholders to drop their resistance to what many analysts expect will become inevitable—a complete sellout to Anheuser-Busch InBev.

Anheuser-Busch first purchased a 17 percent stake in Modelo in 1993. By investing another $1.6 billion, A-B gained control of 50 percent of Modelo’s stock and about 35 percent of its voting power.

Modelo claims 63 percent market share in Mexico. Its flagship beer, Corona Extra, is also the top import brand in the United States.

Although partners, the two companies have butted heads over the years. After a 1994-95 devaluation, Modelo objected to granting Anheuser-Busch a discounted purchase price. It went to international arbitration to solve the matter, and Anheuser-Busch won.

Relations became testy again in the summer of 2008. When Belgium-based beer titan InBev began making offers to buy Anheuser-Busch, the St. Louis brewery considered buying out the half of Modelo it did not already own as a way of making itself too expensive for InBev. But key members of Modelo’s controlling family resisted.

In October 2008, after Anheuser-Busch agreed to sell out to InBev for $52 billion, Modelo filed for arbitration again. It argued its investment agreement prohibited the Budweiser brewer from transferring its interest in Modelo to a competitor without first giving Modelo’s controlling shareholders an opportunity to buy back the shares.

Anheuser-Busch and InBev said Modelo’s claim lacked merit and went ahead with their deal. Yet the arbitration continues. Analysts expect it to wrap up in the next couple of months.

Soon, if Femsa finds a partner, Modelo’s reluctant shareholders will be under renewed pressure from both Anheuser-Busch InBev and some fellow Modelo investors to sell.

Credit Suisse analyst Carlos Laboy says Modelo is inefficiently managed and would benefit from an Anheuser-Busch InBev takeover. And it appears the pressure to do a deal is growing on both sides of the border.

“Modelo has to feel that the world has closed in on Mexico,” Credit Suisse analyst Anthony Bucalo told investors during an October 2 conference call. “There comes a point where the writing is on the wall, and Modelo has to go the way of merging with A-B InBev.”