Easily one of his greatest works, alongside Kickboxer, and the more recent JCVD.
This early entry on Van Damme's repertoire showcases his magnificent fighting skills, agility, and strength.
Bloodsport is loosely based on the life of Frank Dux, real martial artist, who co-produced Bloodsport, as well as serving as the action choreographer. Later, Dux returned to choreograph The Quest as well, also starring Van Damme, despite alleged claims that several feats performed by him go unconfirmed, including his participation in the Kumite tournament.
Nevertheless, this film proves an entertaining one. The build up is rather slow, but as soon as the tournament starts, the fights are plentiful; all well choreographed, and filled with top-notch high flying kicks, roundhouses and grapples.
If you're looking for solid proof why Van Damme was one of the greater martial artists of his time, and need convincing of his skills, either browse the internet and look for his real-life karate tournament accomplishments, listed under Jean-Claude van Varenberg (his real name), or just buy this film, alongside Kickboxer. It will definitely win you over, despite its cheesy dialogues and unnecessary long grunts and screams.
Recommended viewing:
Kickboxer
The Quest
(both with a similar premise of Van Damme entering ring-based fights)