The battle lines in the NFL gay rights struggle will be drawn in the showers ... according to one former NFL star.
Super Bowl champion Raheem Brock -- who spent 10 years in the league -- tells TMZ Sports ... there will be a massive coverup when openly gay players like Michael Sam enter the locker room.
Brock says, "Guys won't go in the shower if they know a guy's gay in there. They gonna feel uncomfortable. I wouldn't [go in the shower]."
He continues, "I mean I would stay at my locker and chill until he's done getting out of the shower."
Brock says his feelings mirror those of a number of active NFL players -- regardless of whether it's politically correct.