A golf ball including a core; a cover layer; and an intermediate layer disposed between the core and the cover layer, the intermediate layer being formed from a composition comprised of a polymer including an acid group fully-neutralized by a salt of an organic acid, a cation source, or a suitable base of the organic acid, the polymer having a first flexural modulus and first tensile strength; and 1 wt. % to 10 wt. % of a chemically-modified nano-clay having a 50% average dry particle size of 6 μm or less, an individual platelet thickness of 1 nm or less, and an aspect ratio of 50 to 1000; wherein the composition has a second flexural modulus and a second tensile strength greater than the first flexural modulus and first tensile strength.