Sponsorship has outperformed all other marketing communication tools in terms of growth throughout the 1990s. The Olympic Games with its huge audience is perhaps the premier place for companies to showcase their brand(s). But an increasing number of corporate contestants find themselves in a gruelling strugle against ambush marketing attempts by their competitors. Ambush marketing is a growing option that has emerged on the heels of the rising costs for securing sponsorship rights. As sponsorship fees demanded by event owners increase, more marketers find the asking price to be outside the reach of their budgets and are forced to look for communication alternatives. Companies that cannot afford to buy sponsorship, or choose not to, may be attracted to an ‘ambush’ strategy for defensive as well as offensive reasons. Ambush marketing represents a way to try to blunt and perhaps even neutralise their competitor's investment. Especially when the official sponsor is non-vigilant, there is growing case evidence of ambush marketing succeeding. So companies buying official sponsorships need to have a strong marketing plan for leveraging their sponsorship investments to minimise any windows of opportunity for would-be ambushers. To the extent that ambush marketing succeeds, it not only defeats the sponsoring company but also risks devaluing the future of corporate sponsorship of events. The Sydney 2000 Olympiad is the battleground for the next major war between sponsors and ambush marketers. The outcome will be important not only to competitors and sponsors but also to the marketing industry as a whole.