We almost got Belmondo in this

Melville said that he thought about offering the part of Vogel to Belmondo, but ultimately went with Volonte after Delon and Belmondo agreed to do Borsalino together. He said that if Delon would have passed on that project, he would have used Le Cercle Rouge as the opportunity to get them together.

Volonte is perfectly fine in the part, and there's not much that can be improved upon in Melville's crime epic. However, Belmondo working alongside Delon (and Montand) in this film would have been unreal. As somebody said in another forum, Belmondo possessed a "shaggy charm", which nicely contrasted with Delon's feline coolness. I can totally see Belmondo in Volonte's part. The fact that Melville hated working with the Italian actor (who was perfectly fine) makes me wish it had happened all the more.

http://jmoneyyourhoney.filmaf.com/owned