An article of footwear includes a sole structure and an upper coupled to the sole structure. The upper includes a lower edge that is disposed adjacent to the sole structure. The upper further includes a collar defining an opening to a void within the upper. The collar defines an upper edge of the upper that is spaced away from the lower edge. The upper includes a forward portion and a heel portion. The heel portion includes a knitted component of unitary knit construction. The knitted component at least partially defines the upper edge and the lower edge of the upper. The knitted component includes a first side edge that is attached to the forward portion along a first side. The knitted component also includes a second side edge that is attached to the forward portion along a second side.