Well, I would be quite a few weight divisions below him (I'm just a little fat right now at about 160 lbs).
If I had to fight him without any weapons or tools, I'd try to take away his main advantages. I can't automatically take his strength, but I can probably get in close enough that I can hit him, too.
Then I'd try to land as many telling blows as I could in 2 seconds! Knees, sciatic nerve, groin, kidneys (if I could reach them). It'd probably be like this, if lucky: Bam-bam (roll) bam-bam (roll) bam-bam (roll) bam-bam (roll away, evaluate). If he looked unfazed, I'd consider the least painful way to kill myself in the confines of wherever we were fighting.
Truthfully, though, from what I've seen: big guys= bigger targets. Some parts of our bodies are fragile, no matter what size we are. Staying alive long enough to strike them- especially with as powerful and probably quick a foe as this- that's the problem!
John