Tripped while attempting a grapple

[Railak]

So someone who doesn't have improved grapple provokes an attack of opportunity when attempting a grapple. And you can use a trip attempt in place of an attack, including an attack of opportunity. What happens if you trip someone who tries to grapple you? This question goes for both 3.5 and Pathfinder.

[Venger]

In 3.5, you follow the rules for tripping (https://www.d20srd.org/srd/combat/specialAttacks.htm#trip) as you would in any other circumstance.

[St Fan]

Of note, however, is this part of the grappling rules:



You provoke an attack of opportunity from the target you are trying to grapple. If the attack of opportunity deals damage, the grapple attempt fails. (Certain monsters do not provoke attacks of opportunity when they attempt to grapple, nor do characters with the Improved Grapple feat.) If the attack of opportunity misses or fails to deal damage, proceed to Step 2.


A successful trip does not normally inflict damage -- though it can in some circumstances, either covered by the rules (unhorsing or using the Great Throw feat) or when the DM decides so (like if the ground is covered of caltrops or spikes, or otherwise dangerous). And of course, a character with Improved Trip can follow up with a standard attack.

Anyway, in the case of the attack of opportunity not inflicting damage, the character could still go through the grapple attempt, since the prone condition doesn't prevent it (he'd just suffer from the usual penalties for the condition). I would imagine this would involve going for the legs, which certainly still counts as grappling.