The cola war is over for the time being, and the winner appears to be Coke — twice.

For the first time ever, Diet Coke has topped rival Pepsi-Cola to become the second-most popular soft drink in the United States. Coca-Cola Classic took the top spot, with more than 1.6 billion cases sold across the U.S. in 2010.

But nearly 927 million cases of Diet Coke were sold last year, besting the 892 million for Pepsi-Cola, said a report by trade publication Beverage Digest released Thursday.

Both companies saw lower sales overall, but the decline was much more pronounced for Pepsi products. Overall, Coke product sales were down 0.5 per cent. Pepsi saw a 2.6 per cent decline.

The achievement is a clear win for Atlanta, Ga.-based Coca-Cola Co. over its rival, PepsiCo Inc. The two have vied for dominance in the domestic U.S. and international markets for decades, before Coke took a clear lead in recent years.

Soft drink sales have fallen for six straight years as consumers switched to healthier alternatives such as juices and tea, and cut back on spending in the recession. The two rivals have moved into bottled water, fruit juices, energy drinks and sports drinks to try to maintain market share.

But the ascent of Diet Coke to the second slot speaks volumes about the growing appeal of diet-branded products in general. Ten years ago, only two of the top 10 most popular sodas were diets. Now four are on the list: Diet Coke, Diet Pepsi, Diet Mountain Dew and Diet Dr Pepper.

Coca-Cola has pumped up its traditional advertising, including online ads that have a new focus on social media. PepsiCo maintained some traditional ads, but also steered dollars toward its Pepsi Refresh Project, an online donation program meant to build brand awareness.

In 2010, to promote its Pepsi MAX drink, PepsiCo updated the classic 1995 ad campaign where two drivers of trucks containing Pepsi and Coke meet in a roadside diner and try each other's soda.