During the 2009 Confederations Cup, Onyewu was paired with Jay DeMerit due to the injury of his normal partner, Carlos Bocanegra, who was unable to play in the group stage. Onyewu played well against Egypt, helping lead the United States to a 3–0 win that earned them a berth in the semifinals. He also had a standout performance in the 2–0 semifinal victory over Spain.