I have an unusual question and I hope you can help me. I'm a fantasy romance writer and know nothing about fighting, although I watch a lot of Muay Thai and kickboxing.
So there's a sparring scene in my book. The main character is a highly trained assassin. In this particular scene, he's sparring with an opponent who is taller, heavier, and physically stronger than him; the opponent also has good technique, though not quite as highly trained. For demonstration purposes, the assassin allowed himself to be pinned to the ground by this heavier guy, who is pressing his knee at the base of his spine, trying to restrict his breathing (the assassin is face down, which is important).
How would the assassin get out of such a position?
What would he have to do exactly, if that's possible? I need to describe it in a couple of sentences and I need it to be realistic. Basically, I want to show off his skill and the ability to get out of a tight spot while fighting an opponent who outweighs him and finding himself in an unfavourable position. He is not allowed weapons.
If that won't work, could you suggest another position and escape that would demonstrate a high level of skill?