How Shield Push affects foes
I think this question may have already been answered, but I cannot find the answer.
When a fighter's combat challenge feature is triggered, he makes an immediate attack. If he strikes his foe, and has the Shield Push feat, the foe immediately takes damage and is also pushed 1 square.
If the fighter's interrupting attack was triggered by an attempt to attack an ally, AND the push moves the foe to a square where it's own attack (which triggered the combat challenge attack) can't reach it's original target, the foe cannot successfully complete it's intended attack.
Right? My understanding is that the entire benefit of Shield Push is to frustrate attacks against nearby allies, that are made by marked foes.
My question is does the Shield Push-ed foe waste it's action and it's attack in a "fizzled" attack? (ala Magic the Gathering, when spells target suddenly invalid targets). Or, does the foe get to change it's plans and use it's action in a more intelligent manner?
Any help is appreciated.