Two Guys

Two Guys
What movie is about two guys who go hunting and one turns into a monster?

I'm looking for a movie I heard about where two guys are out hunting and one falls into a swamp or something and turns into a monster and chases after his friend for the rest of the movie. I know the guy that turned into the monster had a metal plate in his head and that's how you knew it was his friend.

Man-Thing (2005)?
IMDb review:
In the comic series Man-Thing's "secret identity" was Ted Sallis, a scientist whose experiments in the middle of the Everglades swamp lands went horribly awry and turned him into a hybrid man/plant creature with empathic powers. The Man-Thing's name is still Ted Sallis in the film, but he wasn't a scientist in this version; in fact we never even see Ted because he was apparently killed off and buried in the swamp by some evil oil-corporation lackeys before the movie even starts. By the time we join the action, people have been disappearing left and right in the swamps surrounding the Schist Petroleum drill station, and a new sheriff arrives in the sleepy town of Bywater determined to get to the bottom of all the missing persons cases. Of course, he gets more than he bargained for when he starts traipsing through the swamps, avoiding homicidal rednecks and crooked oil-platform workers, and finally finds himself in "The Dark Water," a segment deep in the swamp that's held sacred by the local American Indian population. Seems ole Ted was a bigwig in the Indian tribe which was fighting to keep the corporate types from drilling for oil. Enter Man-Thing, who in this version is apparently some sort of Native American spirit of vengeance, protecting his sacred swamplands by tearing any and all intruders limb from limb.

NOTE: As I do more reading, I'm less certain about "Man-Thing" though I know this has been airing on the Sci Fi Channel occasionally. I'm trying to find the name of a short story that might have been turned into a film, too. For now, this is my only guess. // I found the story: "It" by Theodore Sturgeon"; only, I don't think that it's been filmed.