From ussoccer.com:
http://www.ussoccer.com/news/fullstory.sps?iNewsid=39996&itype=113&iCategoryID=0
Despite losing a thrilling semifinal match to Brazil on Wednesday evening in Miami, the United States is still alive in a bid to secure CONCACAF's lone position at the 2005 FIFA Confederations Cup. The USA's hopes hinge on a victory by Brazil against Mexico in Sunday's championship game at Estadio Azteca in Mexico City. Should Brazil win, and should the United States defeat Costa Rica in the third-place contest on Saturday in Miami, a single playoff game between the U.S. and Mexico will be played to determine the CONCACAF champion. (Costa Rica is no longer alive in this scenario, having lost to Mexico in the semifinals). According to the CONCACAF tournament rules: The CONCACAF Champion will be the team with the highest final ranking. The singular exception to this is when the two highest ranked CONCACAF teams finished second and third in the final standings and the second place team has not played the third-place finisher in the semifinals; in that case there will be a playoff. The playoff match(es) will be played at a date following the conclusion of the Gold Cup at a venue(s), date(s) and time(s) to be jointly agreed by both teams and CONCACAF.
http://www.ussoccer.com/news/fullstory.sps?iNewsid=39996&itype=113&iCategoryID=0