Combine thyme, paprika, pepper, salt, onion powder, garlic powder, cayenne, and cumin in a small bowl; set aside.
Rub brisket all over with liquid smoke, then rub with spice mixture.
Pour Worcestershire and barbeque sauces into a slow cooker; place beef on top.
Cover, and cook on Low, 8 to 10 hours, until fork-tender.
