My MMA fantatic friend re: that suggestion: "if you end up on top you will get triangled or armbarred immediately, if you're aware of those submissions you might have a shot but would still probably lose to kimura or footlock."
Basically I don't think being on the ground vs. this kid would be a good idea at all. Need to hit him really hard in his little face.
Here is Royce Gracie beating someone 2.7 times his bodyweight. At 1:12 mark it's pretty much all over.