Biel, 30, said she was extra nervous about hitting her co-star on the set because they were being directed by Beckinsale's husband Len Wiseman, reported Femalefirst.
"I was so fearful of hitting her. I was thinking, 'Please don't let me hit this woman in the face! Her husband is watching!' And then I hit her," Biel said.
Biel, who plays the film's heroine Melina while Beckinsale is the villainous Lori, said although they fought like men, they were constantly apologising to each other.
