freezing a brisket?

Is the brisket cryovac'd? If so, it should be good for a week or two in a cold fridge.

If not, unless you can use liquid nitrogen to freeze it, ordinary freezing will cause ice crystals to form  in the cells, which then may rupture the cell walls. When cooked, the meat then will loose moisture faster. If you do need to freeze it, use the fastest method possible, such as sumberging it in an ice water bath until it reaches freezing temp, and then put it into the freezer.