A closure having enhanced oxygen barrier capabilities includes a cap body formed from a first material, the cap body defining a cavity therethrough, a stopper formed from a second material, the second material being different than the first material and disposed within the cavity, and a barrier layer formed from a third material, the third material being different than at least the second material and associated with at least one of the cap body and the stopper. A container assembly including a closure and a method of forming the closure is also provided.