Eating the Big FishOnce upon a time, spirited David challenged the towering Goliath. Forty years ago, rental car company Avis challenged Hertzthe big fish in its industryand won a larger, more profitable share of the market by trying harder. Today, Challengers such as method, JetBlue, Nintendo Wii, and Linux successfully compete with much bigger brands in their markets by redefining in their favor the criteria consumers use to make choices. The leaders in any market are