World: Stuart Elliott in America.

In a new twist, the heated, three-way battle for hegemony in the US market for erectile-dysfunction drugs has gone to the devil (Campaign World, 20 August). That's because a new campaign for Viagra, the category leader under pressure from two upstart competitors, is promoting the prescription drug with the provocative device of the devil's horns. The horns are formed by the tops of the letter 'V' in the Viagra logo - in the same shade of blue as the triangular Viagra tablet - that appears behind men's heads in the commercials and print ads. The men have a glint in their eyes and somewhat satanic smiles, intended to underline a roguish cry in the new strapline: 'Get back to mischief.'

This sly approach is a dramatic shift from the tone of several previous campaigns for Viagra, whose market share has been eroding steadily in the last year since the two rival drugs, Levitra and Cialis, were introduced.

Between them, the newcomers have captured about 25 percentage points from Viagra since August 2003, gains that have been attributed partly to the much less conservative tack taken by the ads for Cialis and Levitra.

While Cialis was showing couples side by side in romantic settings, and Levitra was presenting a woman who praised her man's prowess since taking the drug, Viagra was adhering to the motto voiced by Gene Kelly's character in Singin' in the Rain of 'Dignity, always dignity'. The Viagra campaigns have been for the most part staid, sedate, even stuffy; only in recent months, when a commercial from Canada was imported featuring the anthemic Queen song We Are the Champions, did consumers get the idea the drug had something to do with ... you-know-what.

No doubt Viagra's inability ...