Combining power attack and combat espertise

[Mastrolozozzo]

Hi folks!
I'm currently leveling with a pretty straightforward warrior and I was wondering about the rules for combining power attack and combat expertise in d&d 3.5. Lets immagine I have a level 10 warrior with both power attack and combat expertise (and the improved version) and I am fighting a very strong opponent.
I subtract 10 from my attack roll to obtain a +10 to may armor class. I now have a very low attack roll and think: since I can only hit the guy with a roll of 20 I might as well subtract 10 from my attack roll for my power attack feat. Since the description of the feats says you take from your attack roll and not from base attack bonus I am led to think I can actually do this but my master has some doubts. Am I misinterpreting the rules or is there any errata corridge I have not found about this?

[Gandariel]

combat expertise is capped at your Int modifier IIRC.

Anyway that is probably allowed, but i don't see why anyone would do that.
Remember, you get +10 to AC (if that's allowed) for a 95% chance of not doing anything this round

[Cog]

Combat Expertise is normally limited at a difference of 5, so technically you couldn't do that. Taking a penalty of 5 for Expertise and then 10 for Power Attack with only BAB 10 is fine, though.

[Need_A_Life]

Improved Combat Expertise (CW, I think?) raises the cap to +10.

Of course, in D&D offense is the best defence. You'd be better off using a feat to switch the Power Attack penalty to AC, be hit more often, but destroy anything that touches you (Combat Reflexes, Karmic Strike etc.) will help here.

And, better than AC is movement. People can't land an attack if you're outside their reach. Evasive Reflexes and a reach weapon will keep people from landing their melee attacks.
Spellcasters, of course, still have ranges that render movement (almost) useless, so once again, they come out on top.