 Complete the following phrase:  The CONCACAF qualifiers were played between 8 nations, an increase from last years 6, for the first time, between 15 December 2010, in Puerto Vallarta, Mexico, for the third year in a row, seeing Jamaica return after four years and newcomers Guatemala joining the tournament. However, inevitably, the qualifiers were fought out between the strongest four nations in CONCACAF: El Salvador, Costa Rica, Mexico and the United States, who met in the semi-finals of the tournament, clearly dominating as a big four force. However, only the finalists could qualify for the World Cup, which led to two dramatic semi-final games which saw both matches go to penalty shootouts. In the end, it was El Salvador and Mexico who qualified, after tense 3-3 and 1-1 draws against Costa Rica and the United States respectively. The qualifying nations eventually went through on penalties, 2-1 and 1-0 respectively, meaning that El Salvador qualify for the World Cup consecutively after putting out Costa Rica, who qualified last year, whilst Mexico qualify after a two-year absence from the World Cup, meaning the United States have now failed to qualify since 