Oksana Grigorieva: WINNING!

3/6/2011 10:30 AM PST

Oksana Grigorieva: WINNING!

Oksana Grigorieva and her legal team have scored yet another victory against Mel Gibson ... TMZ has learned Mel must fork over an additional $300,000 for her attorney's fees.

Sources connected with Oksana tell us ... Mel must pay the $300k immediately ... per Judge Scott Gordon.

TMZ has been privy to a partial tab on how much Oksana's lawyers -- which total more than 40  -- have requested.  That figure exceeds an incredible $3 million.  Mind you ... it's a custody case involving one kid.

We don't have a tally of how much was actually rewarded, but it well exceeds $1 million, and counting.

Justice -- it ain't cheap.