In a large bowl, combine ground beef, breadcrumbs, milk, onion, minced garlic, egg, salt, pepper, oregano, and basil. Mix until just combined, being careful not to overwork the meat.
Form the mixture into 1 1/2-inch meatballs and place them in the crock-pot.
In a separate bowl, whisk together the tomato sauce and Worcestershire sauce. Pour the sauce over the meatballs in the crock-pot.
Cover and cook on low for 4 hours or until meatballs are cooked through and tender.