Step 1

In a small bowl, mix together the brown sugar, paprika, thyme, salt, black pepper, onion powder, garlic powder, cayenne, and cumin.

Step 2

Rub beef with the liquid smoke to coat, then rub with the spice mixture.

Step 3

Lightly coat a 6-quart oval slow cooker with nonstick cooking spray. Pour in the barbecue and Worcestershire sauce; stir together. Add beef and coat with the sauce.

Step 4

Cover and cook on low until fork tender, for 8-10 hours.

Step 5

Transfer beef to a cutting board; let rest, loosely covered with foil, about 20 minutes.

Step 6

Cut meat across the grain into 1/2-inch slices and serve with the sauce.