Improved Overrun (D20 Modern Feat)
From D&D Wiki
You are skilled at running your opponents down.
Prerequisite: Str 13+, Power Attack
Benefit: When you attempt to overrun an opponent, the target may not choose to avoid you. You also gain a +4 bonus on your Strength check to knock down your opponent.
Normal: Without this feat, the target of an overrun can choose to avoid you or to block you.
Special: An armsman may select Improved Overrun as one of his fighter bonus feats.