Google's rivals are unlikely to get the anti-trust case against the search engine that they want, because the Department of Justice doesn't yet consider online advertising a distinct market, and Mountain View's share of advertising as a whole is less intimidating. But there's one other way to hobble Google, and stymie its acquisition of Doubleclick: raise the alarm about the search giant's scary knowledge of user's interests. If the company that handles an individual's search requests is also serving up the ads, just think of the embarrassing banners that might show up on screen. The tactic has worked before. When acquiring a consumer data company called Abacus in 1999, Doubleclick ran into a storm of protest from privacy advoctates, and an FTC investigation, and had to scale back its plans to merge online and offline consumer profiles. By forcing Google to agree a similar segregation of data, its competitors could undermine the logic of its own grand plan.