Colin Firth, who stars in "The King's Speech," is at the top of Johanson's men's list. Firth plays England's King George VI, who, trying to overcome the stammer he has had since childhood, becomes the student of a speech consultant with unorthodox methods.
"Firth's performance is amazing and even suspenseful, since we never know from one sentence to the next whether he'll even get his words out, and we feel mortified for him," said Johanson. "Firth's work illuminates a powerful story of human perseverance."
James Franco, who portrays outdoorsman Aron Ralston in "127 Hours," also ranked high with Johanson. Ralston frees his arm, which is trapped by a boulder, by amputating it.
"Franco's role, which is essential a one-man show, is about taking a big journey, and it's a marathon performance," said Johanson. "He carries the film."
A nomination could put Franco in an awkward position: He's co-hosting this year's Oscars along with Anne Hathaway.
Jeff Bridges also has a good chance at a nomination for his turn as U.S. Marshal Rooster Cogburn – a role made famous by John Wayne – in "True Grit," in which a young girl hires Bridges to track her father's killer.