Actor Armie Hammer has been left with a black eye after stepping into the boxing ring for a sparring session with a former professional American footballer.

The Social Network star challenged former San Diego Chargers linebacker Shawne Merriman to a bout on Wednesday (19Nov14) at the new Los Angeles gym Unbreakable Performance, but the practice session ended with Hammer nursing a real shiner.

However, the actor, who has been undergoing boxing training for several months, doesn't appear to be too upset by the injury - he is pictured smiling as he shows off his swollen face in a photo obtained by

Ironically, Merriman's nickname on the field was Lights Out.