The biggest hit in last night's Packers vs. Texans game happened before kickoff ... when an NFL Network reporter took an errant football to the face ... during a live shot.

Ian Rapoport was workin' the sidelines at Reliant Stadium in Houston before the game last night, when a football got loose and smacked Ian right in the kisser ... hard.

Gotta hand it to Rapoport ... 'cause he kept his composure and actually laughed at the situation.