Andy Samberg and Kit Harington will lead the all-star ensemble cast of HBO's upcoming sports mockumentary 7 Days in Hell.

Written by Murray Miller, best known for his work on HBO's Girls, 7 Days in Hell follows the fierce competition between two tennis rivals as they compete in an epic 7 day match at Wimbledon.

RELATED: 7 Days in Hell Trailer: Samberg Vs. Harington in an Epic Tennis Match

The movie actually isn't too far fetched. To date, the longest tennis match record, held on Court 18 at Wimbledon, went for 11 hours over the course of three days as John Isner and Nicolas Mahut battled it out during the 2010 Championships.

Also appearing in 7 Days in Hell are Fred Armisen, Lena Dunham, Will Forte, Karen Gillan, Howie Mandel, Soledad O'Brien (playing herself), Michael Sheen, Mary Steenburgen and June Squibb.

Andy Samberg is playing tennis superstar and bad boy Aaron Williams, while Kit Harington will play tennis prodigy and certified truck driver Charles Poole. Karen Gillan is playing a super model vying for both of their attention, which only adds fuel to the fire when the two men are on the court. Though Charlie's best friend, she has made a sex tape with Aaron.

Mary Steenburgen is set to play Charles' controlling and possibly psychotic mother, while Will Forte steps into play a tennis historian.

Jake Szymanski, best known for his work on Saturday Night Live, is directing.