I recently got the chance to roll with a local Judo black belt who has been training for 12 years and says that about 70 % of his matches were won with groundwork. He says that he's probably one of the better ground players of all the Judokas in my hometown. He got me several times with the reverse triangle choke from the turtle position (it was me that was turtled and he was in front of me).
I knew about that move but I've never tried it out and no one had ever attacked me with it before. This guy says that it's one of his favorite moves. How can I counter or stop this move from happening as early as possible from the turtle position?