Stopping someone from getting Kesa


Say the guy is passing my guard and is sliding his right knee over my right knee in the process of getting to Kesa Gatame (he's also holding my right arm). What is the best thing I should do? Or what do you do when this happens? I know there must be a hundred things and it all depends on the situation, but what do you do mostly? Thanks. Hopefully there is enough info in the question..

Place your left forearm across your opponent's neck and your right ahnd on his bicep (lockyour arm out straight. Then put your left knee at his right hip bone and push him back.