Travel Tools - ITA Matrix price difference with aa.com? S vs O class

In my limited use I've not seen Matrix/ITA price out differently than AA.com that often however looking at a number of flights today from DFW to different European cities I'm seeing aa.com pricing at >10% on the same flights returned on Matrix queries. It looks to me like Matrix is returning BA codeshare flights in O class but aa.com always books those segment into S class. Any insight or workaround for this?

Example: AA is $1,103,80 USB and Matrix shows $868.80 USD

DFW-LHR Nov 9 AA 78 (O class)
LHR-BRU Nov 10 AA 6457 (BA codeshare S class on aa.com and O class on ITA)
BRU-JFK Nov 11 AA 171 (O class)
JFK-DFW Nov 11 AA 2033 (O class)

Noticed something similar when checking fares for SFO-MIA. ITA gives amuch lower fare than aa . com

That is interesting. It seems aa.com prefers to select the non-codeshare higher class fare than the lower class codeshare fare. Incidentally, I tried it on hipmunk as DFW-BRU, BRU-JFK, JFK-DFW and it priced it as $1200 then sent me to orbitz to book it where it came up as $868, the same as ITA.

You could try booking it via britishairways.com ?

Pardon my ignorance but what is ITA?

Pardon my ignorance but what is ITA?

http://matrix.itasoftware.com/

Thanks for the link

So ITA is the best place to find fares?