The man who stabbed Mark Sanchez — allegedly in self-defense — was badly injured himself … with new photos capturing the extent of the damage.

Max Lewis — a reporter with FOX59 in Indianapolis — shared photos of a person he says is the other man rushed to the hospital after the early incident early Saturday morning.

Lewis posted the pictures to Facebook … and, they are disturbing — showing a massive, bloody cut on the man’s cheek. The neck brace he’s wearing is filled with blood.

According to Lewis, the man’s family sent him the photo … but they’ve asked him not to publicly identify their family members.

ML did report he’s 69 years old … adding the family says he was “cut in the fight and it went through his cheek and hit his tongue.” Speaking is difficult for him at this time, Lewis adds.

As you know … Sanchez was arrested at the hospital following an incident in Indianapolis during which he was stabbed.

Prosecutors have charged Sanchez with battery resulting in injury, public intoxication and unlawful entry of a motor vehicle.