The actor said, "Django wasn't the lead, so it was like, I need to be the lead. The other character was the lead!"
The other character that Smith is referring to is the bounty hunter, played by Christoph Waltz.
Smith even begged Tarantino to adapt Django's character to be more dominant in the film. "I was like, ‘No, Quentin, please, I need to kill the bad guy!'"
Apparently, this was no meager role for Jamie Foxx, who later took the part.