After nearly a decade mostly doing guest spots on TV, Sarah Baker is getting another turn on the big screen, joining the cast of Warner Bros. laffer “Dog Fight” starring Will Ferrell and Zach Galifianakis.Jay Roach is on board to helm with Chris Henchy and Shawn Harwell penning the script. Originally titled “Southern Rivals,” the story revolves around opposing presidential candidates. Baker will play Galifianakis’ wife. Ferrell, Galifianakis and Roach will produce along with Adam McKay through Gary Sanchez Productions and Everyman Pictures. The part is one of Baker’s first big movie roles; the actress is best known for guest spots on skeins like “The Office,” “Bones” and “Good Luck Charlie.” She also had a small part in the 2002 Reese Witherspoon pic “Sweet Home Alabama.” She is repped by Pakula/King and Associates.