Sweetness is about to be the subject of a bitter courtroom fight.

In one corner is the artificial sweetener in the blue packet, Equal; in the other is its best-selling rival in the yellow packet, Splenda.

The maker of Equal contends that Splenda has been misleading millions of consumers by fostering the notion, through television and print advertising, that Splenda is made from sugar and is natural. Splenda’s maker counters that the process to make the sweetener does indeed start with sugar.

Next Monday, a lawsuit brought by the maker of Equal, Merisant, against Splenda’s maker, McNeil Nutritionals, is scheduled to go before a jury in Federal District Court in Philadelphia.

At stake is leadership of the fiercely competitive $1.5 billion artificial sweetener market. Equal had once dominated the market, finding its way into more than 6,000 consumer products like Diet Coke and Diet Pepsi, the two biggest buyers of artificial sweeteners in the world.