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Corey Cooper has been friends with Glenn Rivers so long, he knew the Clippers coach before he was “Doc.”

“We actually called him ‘Moonie,’ ” Cooper recalled. “His dad was ‘Full Moon,’ his brother was ‘Half Moon’ and he was ‘Quarter Moon.’ “

They grew up across the street from one another in Maywood, bonding over sports.

“Corey has been my best friend since the second grade,” Rivers said by telephone.

When Cooper had a son — also named Corey — on July 2, 1992, Rivers became his godfather.

Both Coopers will be at Ryan Field on Saturday for the Nebraska-Northwestern game. Corey Jr., a 6-foot-1, 215-pound safety, will make his 24th start for the Cornhuskers.

“A very physical player,” Northwestern coach Pat Fitzgerald said.

Corey Sr. will gather with relatives and friends around 11 a.m., more than seven hours before kickoff. He was hoping to accumulate 50 tickets if enough of Corey’s teammates gave their four freebies to the fifth-year senior from Proviso East.

“We’ll all be wearing red,” the elder Cooper promised.

Corey Sr. played safety for Purdue, lettering in 1983 and ’84. Rivers said there was a never a doubt the son would follow in his dad’s footsteps.

“Corey said: ‘He’s a football player. It’s in him,’ ” Rivers said.

Northwestern recruited Cooper, though not as intently as it did Nebraska receiver Jordan Westerkamp, the Montini product who Fitzgerald said “would have looked awesome in purple.”

Asked if he thought he had a chance to reel in Westerkamp, Fitzgerald replied, “I thought we had a great shot until he went out to their spring game and committed.”

A visit to Memorial Stadium in Lincoln, Neb., also mesmerized Cooper.

“Coming in, Coop was as good a receiver as defensive back,” Nebraska coach Bo Pelini said. “We pegged him as a DB and thought he could develop into what he has — a heck of a player, a good leader and a tremendous kid. It’s obvious he was brought up the right way by a blue-collar, hardworking family that has their principles in place.”

Corey Sr. has been a police officer in Maywood since 1990. He used to investigate homicides, but now he’s a sergeant and had a considerably less dangerous task early in the week — providing security during filming of the NBC show “Chicago Fire.”

“They just had a helicopter crash scene,” he said. “It was real neat the way they did it.”

Rivers, who got his famous nickname from Rick Majerus while at Marquette, watched “Little Corey” play in a 2011 game in Lincoln. It happened to be the November day when Northwestern stunned the Huskers.

“After the game they grabbed me and said, ‘Bo wants to say hi,’ ” Rivers recalled. “I said, ‘That’s OK; I’m good.’ Coaches (in all sports) are one step above insane.”

Rivers roots for his godson every chance he gets.

“He has learned a lot of lessons about being patient, handling injuries, waiting your turn,” Rivers said. “You go to Nebraska, there will be a lot of people in front of you.”

And a lot of people at every game — home and away. Corey Sr. never misses one, no matter where it’s played.

“I’m watching every step,” he said.

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Twitter @TeddyGreenstein