The U.S. Open Cup is an annual American soccer competition open to all United States Soccer Federation affiliated teams, from amateur adult club teams to the professional clubs of Major League Soccer (MLS), which has teams in the United States and Canada. In 2009, Major League Soccer was allowed to enter eight of its U.S.-based teams in the tournament. The top six MLS teams from the previous season qualified automatically, while the remaining two spots were determined by preliminary qualification matches.