East Lansing — As Michigan State begins to turn its attention toward the opening of the season, the back end of the defense is starting to come into focus.

With the third week of preseason camp underway, continuing the “No Fly Zone” tradition that has patrolled the secondary over the last few years has been a priority for the Spartans. And while specifics were scarce from Saturday’s scrimmage — Mark Dantonio indicated the offense played well — determining the starting four in the defensive backfield is still not clear.

Safety is all set with fifth-year senior RJ Williamson and sophomore Montae Nicholson. The real battle has been at cornerback.

Junior Demetrious Cox, who has played mostly at safety, is grabbing hold of one corner position, though the idea of playing some safety is still likely.

“It’s nothing for him to kick back in there (at safety),” co-defensive coordinator Harlon Barnett said. “That’s a good thing. He’s gonna have a great year. Demetrious Cox is going to have a great year.”

Cox said he feels more comfortable playing press coverage and getting his hands on receivers. He also believes that the Spartans are better with him at corner.

“I feel like (a corner),” he said. “It looks like the best secondary is gonna be with me playing corner. I’m focusing my technique on corner, I see myself as a corner. I do drills with the corners. I’m still playing some safety, too, but it’s 85 percent corner.”

The real question is who will start at the other corner spot opposite Cox.

There will be plenty expected of whoever wins the job after the Spartans have had cornerbacks taken in the first round of the NFL Draft in each of the past two seasons. The frontrunners are fifth-year senior Arjen Colquhoun and junior Jermaine Edmondson.

For Colquhoun, it would be a significant jump in playing time after seeing spot duty for the bulk of his career.

“He knows this is it,” Barnett said of Colquhoun. “I told him all off-season, ‘this is your opportunity. This is your time. We’re not gonna give it to you.’ He knows that and he’s doing a good job.”

Colquhoun said he has drawn plenty from Darqueze Dennard and Trae Waynes, his former teammates that are now in the NFL. But he also knows he can’t count on being handed the job.

“I’m just bringing everything I’ve got, to be honest,” Colquhoun said. “I can’t pinpoint one thing, I’ll just bring everything I have and on game day just leave it all out there and make plays on the field.”

Some wild cards in the race are redshirt freshman Vayante Copeland, who appears in the top four at this point, as well as junior Darian Hicks, who is back at practice after being diagnosed with mononucleosis at the start of camp. He started 10 games last season but struggled at times.

There are also plenty of freshmen in the mix; Josh Butler, Tyson Smith, Kaleel Gaines and David Dowell are all getting a look.

“It is a pretty intense competition, but I feel pretty good about it,” Dowell said last week. “The older guys are doing a good job of helping us younger guys out. We are just trying to pick it up.”

Barnett said the freshmen have been playing well and he’s glad to have Hicks working his way back. He’s also been happy with the first four corners — Cox, Colquhoun, Edmondson and Copeland.

“The main guys are doing a really good job,” he said. “I’m just trying to get the best out of them.”