Scrub with Lestoil.

With a Power Washer

Try using Easy Off Oven Cleaner. Spray it on and let it sit for about a half hour, not in the sun or it will dry out and will not work. I would say try doing the job as the sun is setting so the brick is cool to the touch. When it has set for half an hour spray it off with the garden hose. It should make it nice and clean. You may decide to do the whole patio this way. It will look new. Good Luck!

There's this product called Mean Green it helps cut grease really great. You can buy this at wal-mart or the Dollar Store

Get the cheapest cat litter you can find and cover the stain then crunch it down, do that a couple of times and it should absorb the grease