The knock-out preliminary rounds themselves were somewhat unusual, with all 38 AFC sides that did not qualify for the 2006 World Cup playing in the first knock-out round, but the 11 best-ranked winners from that round receiving byes in the second round (and only the 8 lowest-ranked winners competing to reduce the fields of teams to 20).
The winners and runners-up from 2 final groups of 5 nations (playing from September 2008 to June 2009) will qualify automatically for the World Cup finals, with the 2 third-placed sides playing off in September 2009 for the right to compete against the Oceania winner, New Zealand, for a final qualification spot (with matches played in October and November 2009).