Green Bay Packers guard T.J. Lang says he's "shocked" by the horrific rape allegations against Oklahoma City police officer Daniel Holtzclaw ... telling TMZ Sports the two were best friends during their football days at Eastern Michigan.
As we previously reported, Holtzclaw -- a standout linebacker at EMU -- is accused of sexually assaulting at least 7 women during his late night shifts with the OCPD.
Lang -- who played at EMU from 2005-08 -- tells us, "He was one of my best friends. I'm totally shocked."
"He was one of our captains. Guys looked to him for leadership.
Holtzclaw is still in custody on a $5 million bond. Lang says the whole situation is sad in every possible way.
"I'm praying for him ... but more importantly I'm praying for the victims."