The post‐global financial crisis world will be increasingly dominated by China and the United States. What the de facto G2 do, together, independently or in conflict, will increasingly define the global bounds of the possible. Both countries want to embed their bilateral diplomacy in the multilateralism of the G20. The problem for the emergent G2 in G20 global architecture is that economic relations between China and the US will be increasingly difficult to manage. The large economic imbalances between the two countries, in which China buys American debt and Americans buy Chinese goods, will endure. Before the crisis, the codependence these imbalances created was a source of stability in Sino–American relations. After the crisis, they will be a source of frustration and conflict, as the second half of 2009 showed. To manage economic relations between China and the US effectively, the G20 agenda will have to move from crisis management to strategic planning for the global economy. The G20 will also have to become more institutionalized, but in a way that resembles more a nonexecutive board of directors of a multinational firm than a management committee of C‐level executives.

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   The world will be characterized by a de facto China–US G2 after the financial crisis.
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   Despite new commitments from both countries, large‐scale China–US economic imbalances will persist.
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   Dueling protectionism and economic nationalism are the biggest potential medium‐term threats to China–US relations.
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   Nesting the de facto G2 in the de jure G20 is the best hope for managing China–US tensions.
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   The G20 should be institutionalized as the board of directors for overseeing the Bretton Woods system, not as a replacement for it.