Allow us to introduce the fighters of this 1949 bout: In the blue corner, Gus Waldorf, a boxer so distinguished that this picture is literally all he's known for. In the red corner, a goddamn bear.
Since they followed boxing protocol as opposed to the bear's preferred combat style of straight up mauling everyone, its teeth and claws were restricted with a muzzle and boxing gloves. And even though the bear went into the ring severely handicapped, Waldorf still lost the fight due to his handicap of not being a bear.
Gus Waldorf / Life
Also the bear was a southpaw, which put him right off his game.
This was not an isolated incident, by the way -- bear-fighting was apparently all the rage back in the day. Here's an Iranian man wrestling a bear in 1951, this time without any of that silly safety equipment.
Dmitri Kessel / Time
Bear knuckle fighting.