Sales of Pepsi Max were up 19.9%, to £124.5m [SymphonyIRI 52w/e 22 January] while sales of Pepsi Cola grew by 19.2% to £106.6m.
Coca-Cola still sells more than other brands, but has seen growth slow. Value sales rose by 4% to £511m, less than the previous year's 6.7% growth, while Diet Coke sales grew by 12.2% to £418.4m, a slight improvement on last year's 11.6% increase.
Pepsi UK licensee Britvic put its success down to strong innovation, marketing and promotions.
"We continued to build our Live Nation partnership, and launched Reward Your Thirst, our most successful on-pack promotion to date," said Noel Clarke, Pepsi brand controller at Britvic.
While both Pepsi and Coke pushed through price increases in 2010, Pepsi's decision to move its 500ml sugar-free and low sugar variants into 600ml bottles at the same price point was described by Nisa-Today's soft drinks buyer Peter Hindmarsh as "one of the best innovations in the category in 2010".
But Pippa Garlick, of branding consultancy Dragon Rouge, argued that Coke's increased emphasis on tradition may backfire.
"They are the classic in the category, but with little [recent] NPD, they have left the door open for a feisty challenger brand like Pepsi."