Warning: SPOILERS for Captain America: Sentinel of Liberty #6
Marvel Comics has finally answered the question of who would win in a fight between Captain America and the Winter Soldier. The two former wartime buddies have gone all out against each other while trapped in the schemes of the Outer Circle, and to everyone's surprise, the one who came out on top was actually James "Bucky" Barnes.
Captain America and Bucky have been best friends since they met in the US Army during World War II. The apparent death of Bucky in their final mission was a trauma that haunted Cap for years after he awakened from suspended animation. It was later revealed that Bucky had actually survived too, but he was recovered by the Soviets who brainwashed him and turned him into the world's deadliest assassin, the Winter Soldier. After Steve Rogers restored his memories, the two friends and war buddies reunited. Since then, Bucky has tried to become a hero to atone for his past, even taking on the mantle of Captain America for a while.
In Captain America Sentinel of Liberty, Steve and Bucky have learned that a mysterious and incredibly powerful organization called the Outer Circle has engineered Barnes' entire life to mold him into the living weapon he is, while the Soviets were just pawns in this game. In issue #6, by Jackson Lanzig, Collin Kelly, Carmen Carnero, and Nolan Woodard, Bucky has just killed The Revolution, one of the Outer Circle's five highest-ranking members, to take his place and dismantle the organization from the inside. Steve is against this course of action and wants to drag Bucky away, even by force. The two come to blows and, after a spectacular battle, the Winter Soldier defeats Captain America.
The Winter Soldier Can Unexpectedly Beat Captain America In A Fair Fight
From the look of the fight, the two were not pulling any punches, even if they were clearly holding back just enough to not kill each other. Bucky's victory is indeed surprising, as on paper Cap should have the advantage. It's true that they are both master fighters with incredible training, expertise, and combat skills, but Steve's Super Soldier Serum should have given him the edge. The Winter Soldier also had his physiology altered by the Infinity Formula (after a blood transfusion from Nick Fury), but that should be way less effective than Steve's original Super Soldier Serum. Usually, Captain America is considered the best fighter in the Marvel Universe, but on this occasion Bucky beat him fair and square, even using Steve's own shield to deliver the final blow.
The power levels of Marvel characters vary greatly according to writers' preferences and story needs. The Captain America vs Winter Soldier debate is one of the hottest that animate the community of Marvel fans, and until now the odds were heavily in favor of Steve Rogers. However, according to the outcome of their latest battle and until their next meeting proves otherwise, the Winter Soldier can beat Captain America.