Emerging regional powers, such as Brazil and India, are reshaping world politics. We conduct a game-theoretic analysis to examine how growing regional powers compete for influence against a global power, such as the United States, in different circumstances. If the global power regards dominant positions in different regions as strategic substitutes (complements), a stronger regional power in region A increases (decreases) the global power’s efforts to dominate in region B. For example, if Iran grows stronger, the United States should increase its efforts to secure energy resources in Central Asia as substitutes for Middle Eastern oil. Conversely, suppose the United States fails to create support for stringent intellectual property rights protection in Latin America because Brazil opposes new rules. In this case, we expect the United States to have fewer incentives to create support in other regions because intellectual property rights rules are most valuable when they constitute a complementary global standard.