Vo filme Poloprofesionál hrajú Will Ferrell (Jackie Moon), Woody Harrelson (Monix), André 3000 (Clarence), Maura Tierney (Lynn), Andy Daly (Dick Pepperfield), Will Arnett (Lou Redwood), Andy Richter (Bobby Dee), Rob Corddry (Kyle), Matt Walsh (Father Pat the Ref), Tim Meadows (Cornelius Banks), David Koechner (Commissioner), Jackie Earle Haley (Dukes), DeRay Davis (Bee Bee Ellis), Josh Braaten (Twiggy Munson), Jay Phillips (Scootsie Double Day), Peter Cornell (Vakidis), Pat Kilbane (Petrelli), Patti LaBelle (Jackie's Mom), Collette Wolfe (Melinda), Jason Sudeikis (Nacho Fan), Kristen Wiig (Bear Handler), Ellia English (Ms. Quincy), Ian Roberts (Spurs Coach), Phil Hendrie (Nets Coach), Ed Helms (Turtleneck), Brian Huskey (White Pants), Paul Rust (Wheelchair Darren), Charlyne Yi (Wheelchair Jody), Rashid Byrd (Tropics Player), Terrell Byrd (Tropics Player), Tyus Tillman (Tropics Player), Michael Westphal (Tropics Player), MaShae Alderman (Ball Girl), Briana Barran (Ball Girl), Karen Berg (Ball Girl), Charlie Gelbart (Ball Girl), Leigha Kingsley (Ball Girl), Kristin Pitts (Ball Girl), Jenica Robinson (Ball Girl), Erinn Selkis (Ball Girl), Sandy Sunshine (Ball Girl), Steve Seagren (Losing Owner #1), Gil Glasgow (Losing Owner #2), Noel Conlon (Man Being Hugged), Scot Armstrong (Cameraman), Steve Bannos (Cop at Jail), Anthony Burrell (Dancer), Dante Henderson (Dancer), Dan Domenech (Dancer), Kate Luyben (Staci Moon (uncredited)), Jerry Minor (Paul the DJ (uncredited)), Tiffany Michelle (Sarah (uncredited)), Charlie Koechner (Commissioner's Son (uncredited)), Gerard Averill (Gerard the Cop (uncredited)), Lyle Stevens (Duke's Buddy (uncredited)), Ralph Kampshoff (Indiana Pacers Owner (uncredited)), Warren Sweeney (Winning Team Owner #1 (uncredited)), Grayson Boucher (Spirits Player #31 / Spurs Player #22 (uncredited)), Bruno Sandoval (Spurs Player #41 (uncredited)), Byron de Marse (Spurs Player (uncredited)), Justen Naughton (Squires Player #31 (uncredited)), James Markham Hall Jr. (Squires Basketball Player (uncredited)), David Sampen (Squires Basketball Player (uncredited)), Kamal Moummad (Starting Point Guard (uncredited)), Quinn Hawking (Basketball player (uncredited)), Ryan C. Burney (Assist. Scoreboard Operator (uncredited)), Danny Mooney (Party Griller (uncredited)), David E. Brown (Avid Tropics Fan (uncredited)), Theo Caesar (Tropics Fan (uncredited)), Sarah Elizabeth Dell (Tropics Fan (uncredited)), Lili Asvar (Fan (uncredited)), Scotty Atkins (Fan (uncredited)), Scott Cordts (Spectator (uncredited)), Laurie Curtis (Spectator (uncredited)), Margaret Newborn (Spectator (uncredited)), Gary Teague (Spectator (uncredited)), Shawntay Dalon (Crowd Member (uncredited)).