I am going for the basic rear collar choke (as seen here), but they are keeping their left arm tight to their body, denying me from reaching under to grab the collar.
Notice how low my grip is on the collar. This may be because I am unable to feed it deeper, or I just plan on doing the following choke already. This choke actually works better with a looser grip; gripping too deeply in the collar can actually put stress on your wrist later.
Unable to get under their arm, I reach down and grab their knee with my left hand.
I pull myself to the knee as I throw my left hook across their body and take out my right hook.
I need to spin out and bring my right leg behind their head before they can put their weight on my leg and prevent me from doing so.
After spinning out, it should be like they've fallen backwards into the space you opened up. Notice how I am sitting up, not letting my hips be trapped under them. You know you've got it right when their head is resting on your thigh. Keep ahold of their knee so they can't run or roll away.
To defend the choke, Greg has reached up and grabbed my arm to try to pull it over his head, which will stop it.
To prevent this, I throw my legs over his arm until I've pinned it then I cross my ankles. Do this whether or not they attempt the defense. I just taught it in this context to show you how to stop a common defense.
The important detail at this point is to make sure your calf is on their shoulder in order to lock down their upper body.
You'll find that if you keep working to trap this arm, you'll catch it like it's in the crucifix or even put them into triangles.
To finish, I lay back and arch my shoulders, pulling on the lapel and the knee. The grip on the knee prevents them from turning away from it. This is a really powerful choke since it puts your entire back into it.
