The Best Actor field for the 2010 SAG Awards is a little crowded. Even so, I'd say that four actors have a lock on a nomination: George Clooney for his corporate-downsizing expert in Up in the Air, Jeff Bridges for his country singer in Crazy Heart, Morgan Freeman for his Nelson Mandela in Invictus, and Colin Firth for his bereaved college professor in A Single Man.

The fifth slot, however, is up for grabs. Jeremy Renner is a strong possibility, especially considering that Kathryn Bigelow's Iraq War drama The Hurt Locker is sure to get a Best Ensemble nod. That said, it's just as possible that Daniel Day-Lewis gets shortlisted for Nine, even though neither the film nor his performance has created many waves among critics. But then again, the Hollywood Foreign Press Association surely liked both Day-Lewis and Nine well enough to give them nominations in their best comedy or musical section.

Joseph Gordon-Levitt got a surprising Golden Globe nod and has a pretty good chance of getting some SAG Award recognition as well. After all, (500) Days of Summer was a well-received sleeper hit, and Gordon-Levitt is at the film's core. Viggo Mortensen's The Road hasn't been getting all that much love from film critics' groups, but it's quite possible that Mortensen's fellow actors will want to honor him for his difficult role in John Hillcoat's futuristic drama.

Strong possibilities:

Matt Damon, for his whistleblower in The Informant!

Daniel Day-Lewis, for his Italian filmmaker in Nine

Viggo Mortensen for his father striving to protect his son in a post-apocalyptic world in The Road

Joseph Gordon-Levitt for his youth in love in (500) Days of Summer

Possibilities:

James McAvoy in The Last Station (above, with Paul Giamatti)

Robert Downey Jr in Sherlock Holmes

Robert De Niro in Everybody’s Fine

Michael Stuhlbarg in A Serious Man

Ben Foster in The Messenger

Tobey Maguire in Brothers

Hal Holbrook in That Evening Sun

Less likely:

Ben Whishaw in Bright Star (above, with Abbie Cornish)

Brad Pitt for Inglourious Basterds

Jake Gyllenhaal in Brothers

Clive Owen in The Boys Are Back

Michael Sheen in The Damned United

Peter Sarsgaard in An Education