Answer:
United States vs Italy
Explanation:
Since the moment United States entered the war in December of 1941 they were one of the key elements to the victory of Allies. They managed to defeat Japan on their own, to help Britain crush German power in Africa, they contributed the most to the capitulation of Italy after attack on Sicily, and also with Operation Overlord contributed a lot to the destruction of Nazi Germany.
On the other side, Italy was the weakest links among Axis powers. The area which they were holding under their control were the areas where rebellions and uprisings were spreading fastest. They capitulated in September of 1943 thus leaving Germany practically to fight on their own against Allies.
