The news of first-round pick Dre Kirkpatrick's injured knee tore through Twitter and the Bengals fan base this week, but he's far from the only DB in the training room. CB Nate Clements admitted Thursday he's still suffering from the abdominal/groin issue that kept him out of OTAs in June. With Leon Hall returning from an Achilles tear, that makes for half of this deep crop of corners battling injury concerns as camp opens Friday.

Marvin Lewis offered little more information on the Kirkpatrick injury other than reiterating his comments from Wednesday on 700WLW that the injury is a "small thing." He didn't place a timetable on a return, though the standard recovery is believed to be in the vicinity of four weeks.

Hall is expected to be full go or close to it Friday, but he's still a question mark coming off such a serious injury. The 32-year-old Clements, who started across from him last season, may be the bigger concern. A veteran that far up in age struggling for two months with a lingering injury is far from the ideal scenario.

"I'm doing what the trainers ask me to do," Clements said. "I can't put no timetable on it. It's not really going slower than I thought, it's just with these types of injuries you really have to take your time because a groin or hamstring injury can be one of those things that can keep lingering on."

With Clements, Kirkpatrick and Hall all under the eyes of the trainers, only Adam Jones, Jason Allen and Terence Newman remain among the healthy. Toss in 2010 third-round pick Brandon Ghee, who is healthy but fought injuries every step of his NFL career, and there will be plenty of reps to go around in this competition.

Follow Vikings reporter Paul Dehner on Twitter @CBSSportsNFLCIN.