Starbucks, which was one of Fallon's first clients after it launched in 1998, is said to have asked RKCR/Y&R to create a seasonal campaign in time for the autumn. The remaining advertising account is expected to follow suit.
James Murphy, the managing director at RKCR/Y&R, said: "We are working with Starbucks on a coffee-related advertising campaign to run across autumn.
"The campaign will focus on their sourcing, roasting and brewing of the world's finest coffee."
Although Starbucks has raised its profile through PR promotions, with a lesser focus on above-the-line ads, Fallon's work for Starbucks has been award-winning over the years.
The agency's "desk" ad, which was created by Richard Flintham and Andy McLeod, was awarded silver at the 2002 Campaign Poster Awards in the best grocery, soft drinks or household poster category.
Starbucks competes in a rapidly expanding marketplace, with brands such as Nescafe launching portable line extensions to challenge its dominance of the take-away coffee market.
The chain is also set to face stiffer competition from McDonald's, which is stepping up its coffee shop offer to make up for the flagging popularity of some of its traditional lines.