Two-On-One: Getting the Back

In this series you see blue shirt attacking gray shirt with a palm, and gray shirt blocking (badly). Blue shirt uses this block to get the arm control and yanks gray shirt into a rear naked choke (unfinished in the images below).

Blue shirt attacks with a palm and gets the arm control or two-on-one when gray shirt blocks...

...and pulls him into a rear naked choke.

Back to the clinch.