When a typical creature makes an invasion attempt against an enemy, that enemy can choose to avoid that creature. That enemy does not roll to avoid the creature, the enemy stays in its space and the enemy does not suffer adverse effects. The creature that made the invasion attempt continues to move normally, although the creature has expended its standard action to make the invasion attempt. (The special attack invasion specifically says that the creature can make the invasion attempt during its movement action: "In general, you can not perform a standard action during a movement, this is an exception" (Player's manual 157).)
So, yes, if a goblin warrior stands between Regdar and the goblin warlord, when Regdar makes the attack attempt on the goblin warrior to reach the goblin warlord, the goblin warrior can simply say: "So It is, sir! " and let it pass.
It takes a feat like Improved Overrun (PH 96) or a special ability for the creature that is trying to invade the enemy. do not to avoid it!
Note: The player's manual Errata removes the option of an overrun attempt from the special attack charge.