Watch Kit Harington, Andy Samberg in trailer for HBO's mockumentary

It's Andy Samberg versus Kit Harington in new trailer for HBO's upcoming comedy '7 Days in Hell.'

The comedy also features Karen Gillan, Lena Dunham, Michael Sheen, Mary Steenburgen, Will Forte, Howie Mandel and Fred Armisen alongside real-life tennis stars John McEnroe and Serena Williams.

Plot.

"A fictional documentary-style expose on the rivalry between two tennis stars who battled it out in a 2004 match that lasted seven days."

Written by Murray Miller and directed by Jake Szymanski,'7 Days in Hell' will premiere July 11 on HBO.