DURHAM Sophomore Conner Vernon said he thinks Duke's receiving corps can be the best in the ACC.

But it needs to get healthy, first.

Although Vernon and All-ACC wideout Donovan Varner returned to limited practice on Tuesday morning, Austin Kelly - the third starting receiver in the group - sat out. Kelly and Vernon sustained hamstring injuries during Monday night's scrimmage, while Varner sat out the scrimmage because of a sore hamstring as well.

Coach David Cutcliffe said the wear and tear of training camp had affected the trio, but he expects them to be healthy by the season opener against Elon. They accounted for more than 2,400 receiving yards and 15 touchdowns last season.

"When we can get them out there, it's certainly going to make a difference," Cutcliffe said during Tuesday's media day news conference. "We have three guys that caught, what, 170 balls the previous season. So they've been good with (new quarterback Sean Renfree) all summer. You know that they know each other, and they've got a lot of confidence with Sean.

"But it's probably good that he's working with all those guys that are, quote, back-ups. Hopefully we can play some (more) people, particularly early in the season. One of our goals is to play more people than we've been playing, anyway, and certainly receiver would be part of that too."

D-Line hurting also: The Blue Devils' defensive line is already thin, and injuries aren't helping matters there, either.

"We've got (redshirt freshman) Sydney Sarmiento out with a knee, and (senior Wesley) Oglesby out with an ankle and (redshirt freshman) Desmond Johnson out with a foot and (freshman) Nick Sink," Cutcliffe said. "I could go on and on and on, and that bothers me a bit, because those guys need a bunch of work."

Sarmiento, a reserve defensive end, hurt his leg last week and was scheduled for an MRI Tuesday afternoon.

Duke, which played a 4-3 defense last season, is going to a defensive scheme that will utilize multiple looks, including a 3-4.

But it returns little depth up front, thanks to the graduation of starters Vince Oghobaase and Ayanga Okpokowuruk, and the dismissal during the offseason of freshman defensive tackle John Drew and freshman defensive end Brandon Putnam after they were charged with felonious possession and discharge of a weapon

Asked if Duke could make it through the season without playing any true freshmen on the defensive line, Cutcliffe called that "the hundred-dollar question."

"That's a day-to-day situation in evaluating what we have available, and who we have," he said. "I don't want to destroy kids' confidence, who are not ready to play in the trenches in the ACC. I think we've got some headed in that direction, but I'm not ready to put a stamp of approval on it yet."