Qualifying criteria
The ranking of each team in each group will be determined as follows:
a) greatest number of points obtained in all group matches;
b) goal difference in all group matches;
c) greatest number of goals scored in all group matches.
If two or more teams are equal on the basis of the above three criteria,
their rankings will be determined as follows:
d) greatest number of points obtained in the group matches between the
teams concerned;
e) goal difference resulting from the group matches between the teams
concerned;
f) greater number of goals scored in all group matches between the teams
concerned;
g) drawing of lots by the FIFA Organising Committee.
http://www.fifa.com/worldcup/standings/whatif.html