The 6-foot-2 McKeon, who trained with the USA earlier this year in Orlando, will remain in Denver this weekend and will be available for the Colorado Rapids' MLS match on Sunday against the Tampa Bay Mutiny. He will join the U.S. team on Monday. McKeon has never appeared for the National Team in a full-international match.
Armas, who has played in the last seven matches for the U.S. National Team and has developed into a valuable defensive midfielder, suffered a grade-one sprain to the medial collateral ligament of his left knee during a scrimmage on Tuesday. He left the U.S. camp this evening and will continue his rehabilitation with his Chicago Fire club.
The change is the latest in a developing U.S. National Team roster. Last week the U.S. called in John Harkes as a replacement for David Regis, who was deemed not fit to play after developing swelling in his left knee.
The United States will open the Confederations Cup this Saturday against New Zealand(2:30 p.m. CT), continue on to face Brazil on July 28 (8:30 p.m. CT) and will close out group play against reigning European Champions Germany on July 30 (6 p.m. CT). All three of the USA's matches - and the entire Group B schedule - will be played at the Jalisco Stadium in Guadalajara. The matches in Group A, which include Mexico, Egypt, Bolivia and Saudi Arabia, will take place at the Azteca Stadium in Mexico City. Only the top two teams in each group will advance to the semifinals.