Can a creature with reach using Sunder be targeted by an AoO if it isn't within range of the defender?

Question

Let's assume that the large creature with reach weapon (reach 20') does not have a feat to not provoke AoO.

And a medium humanoid with a longsword (reach 5') is standing out of his own reach but in reach for the Large one.

The large creature goes for a sunder attack.

The sunder combat special action of 3.5 SRD says

SUNDER

You can use a melee attack with a slashing or bludgeoning weapon to strike a weapon or shield that your opponent is holding. If you’re attempting to sunder a weapon or shield, follow the steps outlined here. (Attacking held objects other than weapons or shields is covered below.)

Step 1: Attack of Opportunity. You provoke an attack of opportunity from the target whose weapon or shield you are trying to sunder. (If you have the Improved Sunder feat, you don’t incur an attack of opportunity for making the attempt.)

Should that be only if the medium one can reach him?

or given by RAW, screw physics?

AND

An extra question...

is in pathfinder (besides the CMB CMD stuff) anyway different?

Answer 1

In D&D 3.5...

Threatened Squares
You threaten all squares into which you can make a melee attack, even when it is not your action. Generally, that means everything in all squares adjacent to your space (including diagonally). An enemy that takes certain actions while in a threatened square provokes an attack of opportunity from you. If you’re unarmed, you don’t normally threaten any squares and thus can’t make attacks of opportunity.

The creature with reach is not within the longsword-wielder's threatened area when it made the sunder attempt. Thus the creature with reach doesn't provoke attacks of opportunity from the longsword-wielder when it attempts the sunder.

In Pathfinder...

Threatened Squares
You threaten all squares into which you can make a melee attack, even when it is not your turn. Generally, that means everything in all squares adjacent to your space (including diagonally). An enemy that takes certain actions while in a threatened square provokes an attack of opportunity from you.

So same thing.

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Although neither D&D 3.5's sunder ("You provoke an attack of opportunity from the target whose weapon or shield you are trying to sunder") nor Pathfinder's sunder ("You can attempt to sunder an item held or worn by your opponent in place of a melee attack [...] If you do not have the Improved Sunder feat, or a similar ability, attempting to sunder an item provokes an attack of opportunity from the target of your maneuver") specify that the attack of opportunity by the defender is contingent upon the defender's reach, neither must. While the creature making the sunder attempt provokes the attack of opportunity, the creature making the attack of opportunity is limited to making attacks of opportunity--under normal circumstance--only within his threatened area.