The chapter examines the onset of great-power competition between the rising power, China and the dominant power, the United States. It first discusses how Xi Jinping consolidated central control of foreign policy, the economy, and the military. The next section sketches out the main ideas and initiatives in Xi’s major-power diplomacy. The following section discusses how the long standing US engagement policy came to an abrupt end, ushering in a new phase of US-China peer competition. A further section teases out the key beliefs held by the Chinese leadership and policy elites on the emerging great-power struggle. The conclusion highlights how China mobilized and adjusted its diplomacy amid the Sino-US rivalry to secure its long-term strategic opportunity.