Go to dog fight/threaten the back. If the leg that is locked down is becoming stiff and therefore is no longer applying the knee to the mat for base you should be able to take advantage of that and snake your way to the dog fight if you have the under-hook. if you don't have the under-hook, then the stomp to butterfly is usually your best bet. If he smells the dog fight coming and hits you with a hard wizzer then immediately go Plan B off his reaction. Timing is everything there as he will just reset his weight on you if your not taking advantage of the momentum.