James Caan received his first Oscar nomination for portraying Sonny Corleone in The Godfather.
Caan is simply absolutely right for Sonny, and just everything which he does in the role is exactly as Sonny should be. Caan as an incredible intensity in the role, always showing it as an almost overpowering intensity which he tries to intact to situations even when it is not the best choice for the situation. Caan has the perfect way of showing Sonny's temper, in a hair trigger fashion with the right incredible sting when it fully comes out in his fully emotional and fully convincing reactions.
Caan's performance is a strongly physical and charismatic performance. Caan really energizes the screen well in his was of always commanding, and always have a strong presence whenever he is in a scene. Caan leaves no doubt of Sonny presence in the crime family, because of this command and naturalism in his performance. Every single thing which Sonny does is Sonny, and every thing he does is completely and utterly made true to the character because Caan absolutely becomes Sonny in this role.
Caan's performance is also very interesting because despite the intensity of the character of Sonny, Caan remains likable as Sonny as well. Caan has tremendous charisma in this role which works incredibly well. One aspect Caan also excels in particularly well which could have easily been forgotten in a performance like this, and that is showing a tender side of Sonny which is for his family.
Now Caan very astutely never completely shows tenderness in his performance, but rather shows it in a subtle rather small fashion. Caan shows this well in his scene where he gives the quiet talk to Michael (Al Pacino) just before Michael really becomes part of the family business. Also his moments with his sister Connie after she is beaten by her husband (Talia Shire) where he shows his anger well, but also a genuine care for his sister which is spectacularly done by Caan. I think these moments in particular allowed Caan to show a greater depth of Sonny. Overall Caan gives a strong, intense performance, the type of performance that makes it so I really could not see anyone else in the role besides Cann.