Simon Lowden, chief marketing officer at PepsiCo North America, told USA Today the Amazon rollout "lets PepsiCo use a high-profile channel to gauge initial response. 

It also allows the product to get some scale and awareness before it goes into the bottler system."

A Pepsi spokesman further told Reuters the decision follows online successes for Pepsi's other products. Starbucks Double Shot Light, sold through a joint venture with Starbucks, is Pepsi's top-selling online item year-to-date.

The Amazon launch,set for mid-October, comes amid a near decade long declining sales trend for carbonated soft drinks. The beverage giants have been experimenting with launch strategies.

"The bottling systems do better with more established products," John Sicher, editor and publisher of Beverage Digest, told The Wall Street Journal. "If they [Coke and Pepsi] launch a product and build scale with Amazon before expanding to retail presence and it works, that's a good move."

Pepsi True's distinction is that it is made with sugar and stevia, a natural sweetener, and containing about 30 percent fewer calories than regular Pepsi. It includes no high-fructose corn syrup or artificial sweeteners.

In a similar introduction, Coca Cola in September brought back Surge, a soda discontinued 12 years ago, exclusively through Amazon and has seen continued sell outs. It plans to eventually return Surge to its regular distribution channels.

For Coca-Cola Life, a mid-calorie cola similar to Pepsi True, however, Coke chose to test the line in some stores in the Southern United States before planning national rollout for November.

• Real Cola Taste. True Pepsi Fun. - PepsiCo
• Pepsi True to launch only on Amazon - USA Today
• New Pepsi Goes to Amazon - The Wall Street Journal (sub. required)
• Pepsi to launch naturally sweetened soda on Amazon, bypassing stores -Reuters
• CNET Internet You can only buy this new Pepsi in one place - CNET
• Amazon and Coca-Cola partner on niche nostalgia e-commerce - RetailWire