In a small bowl, combine the soy sauce, brown sugar, tomato paste, Worcestershire sauce and the garlic powder. Pour this mix into the crockpot.
Now, slice up the chicken into chunks and drain the pineapple juice from the pineapples. Toss these two into the crockpot as well. Next, turn the crockpot on high and cook for 3 hours.
In the middle of the cook give the chicken and sauce a stir. When finished serve over a bed of rice.