Ogilvy & Mather is poised to win the consolidated global and North America Coke Zero creative business, according to people familiar with the situation.

Ogilvy had handled the brand abroad while Droga5 had been responsible for marketing in North America. The brand's creative has not been exclusive to those agencies, however -- McCann subsidiary Fitzgerald & Co. handles assignments for the brand, including a college football campaign starting later this month.

"Droga5 and Ogilvy are great roster agencies of ours here in North America and around the world. We're constantly evaluating ways to work with them across our portfolio of brands in new and different ways," said a Coca-Cola spokeswoman, declining to comment further.

The review pitted Ogilvy against Droga5's London office. Droga5 won the North America business from Crispin in 2012, while Ogilvy won the global business from Wieden & Kennedy, Amsterdam, in 2010.

"Coke Zero was a U.S.-based business for a few years and recently they consolidated the U.S. and global business," a Droga5 spokeswoman said. "Our London office pitched it with help from the New York team. We declined to pitch it out of New York." She declined to elaborate.

According to executives familiar with the matter, executive moves at Coca-Cola prompted the company to centralize its Coke Zero marketing account. In May, star Coca-Cola marketer Wendy Clark was appointed president-sparkling and strategic marketing, Coca-Cola North America, moving over from a global role. At the same time, Katie Bayne, who had been president-North America Brands and is the former CMO of Coca-Cola North America, took on the job of senior VP-global sparkling brand center.

The Coke Zero brand has been growing rapidly in global markets. In Europe, for example, it is poised to surpass Coca-Cola Light, becoming the market's second largest soda brand.

Coke Zero spent $41 million in measured media in the U.S. in 2013, according the Kantar Media.

Contributing: Natalie Zmuda