(philip seymour hoffman in "the master")
Unlike in the contest for Best Actor and Best Supporting Actress, in which it's almost a foregone conclusion who will win the Oscar, and in the Best Actress category, in which the race is really only between two women, the Best Supporting Actor Oscar could go to four or five different men. There are some frontrunners, but they don't have a lock on a win by any means.
The Frontrunners: Three men have won the majority of the critics awards, Tommy Lee Jones, Philip Seymour Hoffman and Christoph Waltz, and they've all previously won Oscars, which gives them important street cred with Oscar voters.
(javier bardem in "skyfall")
Theory: We'll go ahead and guess that Jones, Hoffman and Waltz will get the first three slots, and after that, it's anybody's guess. If DiCaprio doesn't get one of the two remaining nominations, it will be because another actor from his movie, "Django Unchained", already has a nomination, and the Oscar voters usually prefer to spread the wealth around to different movies. There will be a lot of peer pressure to nominate someone from "Beasts of The Southern Wild", so if the lead actress in that movie doesn't get a nod for Best Actress, then Dwight Henry could get the nod to represent the popular, sleeper movie. And then there's Matthew McConaughey, who the voters are practically drooling to reward for "Magic Mike". But McConaughey made a poor showing in the critics awards season, so the Oscar voters might be afraid a nomination for him could be ridiculed. There's also Alan Arkin, a previous Oscar winner, who is the only person likely to get recognized for the immensely respected "Argo", so you can't count him out. And Javier Bardem turned in an absolutely deliciously subvervise performance in "Skyfall", so he's a possibility as well.
Prediction: Jones, Hoffman, Waltz, Arkin... and either DiCaprio or Bardem.