Apparently, Chris Evans and Frank Grillo couldn’t get the elevator fight scene in Winter Soldier to look authentic (due to the confined space) without actually whaling on one other. So that’s exactly what they did.
Frank Grillo mentions they were covered in bruises for days from the filming of the scene. Frank tells
Entertainment Weekly in an interview:
“There were a couple times in that elevator scene where [Evans] said, ‘Dude, you’re hitting me,” Grillo recalled for the magazine. “I go, ‘We are in an elevator. My stunt guy’s not coming in here. They won’t be able to shoot your face. We gotta do this.’ And we just start punching each other. We did that scene for six days. We were literally covered in black and blues. That’s why I love him.”
Apparently Frank Grillo has extensive background in martial arts: