Oscar nominations haven’t been released yet (and they won’t be for another month), but oddsmakers are already betting on “12 Years a Slave” to win gold. According to new odds released by the betting company Bovada, “12 Years a Slave” is leading the pack for best picture while its star Chiwetel Ejiofor should take home best actor. The film is tied with “Gravity” for best director and Cate Blanchett is a shoe-in for best actress for “Blue Jasmine.” However, if past experience holds true, the best chances lie with the Academy surprising the heck out of us all and denying someone we thought was a sure thing.

Really, when it comes to the Oscars, is there really any way to tell what the voters are going to do? It almost seems like it is more of a game of campaigning and momentum. Just ask Ben Affleck, whose “Argo” was last year’s surprise best picture winner. Remember in December how Steven Spielberg’s “Lincoln” was supposed to be the frontrunner until the snubbed Affleck, who wasn’t even nominated for directing, started to campaign like a seasoned politician? Not working on another project until after the Oscars, the Cambridge native was basically kissing babies and shaking hands full-time.

Of course, the true test of a film’s award season strength, and the kickoff of the first real push of momentum for a film, is the Golden Globes. But then again, past winners of the Globes haven’t always fared well at Oscar time. Again, ask Ben Affleck. Last year, he won a Golden Globe for directing and wasn’t even nominated for an Oscar.

See? Predicting the Oscars is impossible. At times they can be undecided or as fickle as your grandma. So, before you run out and start betting with your friends and family on who is going to make those long and overly dramatic acceptance speeches, here is our list of the top five best picture upsets.

1. 1995: ‘Braveheart’ wins best picture over ‘Apollo 13′
For some members that weren’t producers and directors (they had picked “Apollo 13”), the top film of 1995 would naturally be “Braveheart.” Back then, no one would have thought Mel Gibson would be end up being basically shunned for his series of ranting public breakdowns. Since the Academy likes to recognize an individual’s body of work and possibly to remind them of the glory days, voters chose a sweeping epic that used to be a regular staple of Hollywood.

2. 1991: ‘Dances With Wolves’ wins best picture over ‘Goodfellas’
Another big upset for those mob movie fans is 1991’s “Dances With Wolves,” which beat out Martin Scorsese’s mafia masterpiece “Goodfellas,” as well as “Awakenings,” “Ghost,” and “Godfather: Part III.” Kevin Costner’s western (a dying film category), featuring Indians and horses with romance thrown in, ended up toppling a Scorsese film to sashay its way to an Oscar win.

3. 1977: ‘Rocky’ wins best picture over ‘Taxi Driver’
That’s right: “Taxi Driver” never won best picture. Why? Because the film lost to “Rocky” at the 1977 Oscars. In a true tale of the underdog taking home the glory, the then-unknown star Sly Stallone’s little film knocked out names like Redford and Scorsese.

4. 2006: ‘Crash’ wins best picture over ‘Brokeback Mountain’
One of the biggest upsets in recent history (Don’t believe us? Google “Brokeback” and “biggest upset”) for best picture was “Crash,” a film that came out of nowhere to steal the nights top honor from odds-on-favorite “Brokeback Mountain.” Boasting an impressive cast, the win for “Crash” still left most in the audience flabbergasted and even the cast outright shocked.

5. 1999: ‘Shakespeare in Love’ wins best picture over ‘Saving Private Ryan’
There is one time that you can feel sorry for Steven Spielberg and Tom Hanks. That’s because their WWII epic “Saving Private Ryan” lost to Harvey Weinstein. He was able to see the allure of rewriting “Shakespeare in Love” as a romantic comedy about “Romeo and Juliet.”