Mustrum_Ridcully
Legend
The barbarian just has to grapple the fighter. Unless he his focussed and specialisized in unarmed combat (or with his spiked gauntlets/armor spikes), his main advantages are away, while the barbarian still benefits from his increased strength due to Rage. The only problem for the barbarian is that a succesful AOO will negate the grapple attempt - but since the fighters Touch AC will probably suck (Dex Bonus +1, +5 Deflection at 20th level?), he has several attempts...