Oksana Grigorieva -- Preparing for Battle

11/22/2010 10:00 AM PST

Oksana Grigorieva -- Preparing for Battle with Mel Gibson

Oksana Grigorieva was spotted out and about on Sunday -- meeting with her legal team and preparing for her legal showdown today with Mel Gibson.

As we first reported, Mel Gibson will  show up in court to telegraph how serious he is ... trying to wrestle custody from Oksana on grounds she is not acting in the best interests of Lucia. He's also asking the judge to deny Oksana overnight visits, and to grant her supervised visitation.

Mel and Oksana, face-to-face again ... should be an interesting day in court.