Biggest problem is the laziness of construction, quickly evidencing a "rush to porn" bias that spoils the overall effect. In both this Part 3 edition as well as Part 1 of THE BOXER (ROCCO THE Italian STALLION), the movie begins with a lengthy all-sex scene lasting a couple of reels, reuniting Siffredi with his classic TARZAN X co-star Rosa Caracciolo. Both times it makes the rest of the movie literally an anti-climax, especially since it's Rosa's only sex scene and she is underused dramatically.
This rookie mistake doesn't compute with D'Amato having directed 200 films in his career, most of them before attempting his boxing trilogy. In TARZAN X, almost universally hailed as the best porn movie of his career, he balanced the sex with story, and also had Rosa (memorable as Jane) front and center throughout. Even just on a formula level, how did he fail to realize that she (and her saga) is what made that film work so well?
Siffredi, undoubtedly a bit pooped after humping his way through 182 minutes of THE BOXER, gets spelled in the sex department this time out by sharing lead cocksman duties with Hakan Serbes, well-cast as a young boxer named Leone who worships Rocco, but hasn't made it in the biz, working as a handyman (all the better to hump the lady of the house). Serbes was an odd (and unsuccessful) choice by Big Joe to impersonate Rudolph Valentino in the XXX biopic RUDY, but with shaved head he's effective here as a nobody.
Drama is introduced with Rocco accidentally killing a contender Svensen in the ring, causing him to decide to retire. Guest star slimy Max Hardcore (in a non-sex role, thank God!) plays a slimy boxing promoter named Snake who offers itinerant Leone $10,000 for training and promises his huge fees ($300,000 per round still standing upright plus a $1 million bonus if he wins) if he can get Rocco to fight him in a match.
Rocco gets the bad news he has a hematoma, so fighting again is not recommended. (Oddly D'Amato sloppily introduces and later drops this subplot, typical of his "all I care about is the sex scenes" approach.) Rocco turns down a $50,000,000 offer from Snake to fight, so Snake asks Leone to provoke him, and get a street fight going. All Snake needs to know is where it will take place, and he will handle the rest (presumably with some mobile camera setup like that used for MSG TV feeds).
Per the film's title, the duo brawls one night in a remote spot, with Rocco emerging the winner. Happy ending has Rocco & Marta (Caracciolo) back together, and Snake is happy with a surreptitiously shot videotape of the private fight, for lucrative telecasting back in Italy. Go RAI!
As in the previous films, Rocco & Rosa speak to each other in untranslated Italian. The rest of the film is shot in direct-sound English, with both Rocco and Hakan barely intelligible, having extreme trouble articulating this time in the foreign tongue. The boxing scenes are poorly done.
Best element of the movie is casting of a short-short beautiful and enthusiastic blonde actress (I'm guessing she's played by Barbie Angel, but can't make a positive ID), who has the most sex scenes. She's the closest thing to seeing Hayden Panetierre in a XXX role.