A.J. Green has been his dynamic self this spring.

Wide receiver Cody Core, perhaps the Bengals' most improved player in the spring camps, went down late in Wednesday's practice with what appeared to be a bruised ankle. The Bengals didn't comment on the injury, but indications late Wednesday afternoon were he'll be ready for training camp.

It sure looked a lot worse than that.

As Core rolled around on the Paul Brown Stadium turf hugging his left knee to his chest in severe pain, head coach Marvin Lewis cut short the middle practice of the three-day mandatory camp. It was unclear if it was because of Core's injury or the thunder rolling through the stadium, but he was carted to the X-Ray room.

Core emerged a few minutes later straight-legged but left foot not touching the ground with trainers Keith Justice and Dan Willen on either side of him.

After wide receiver Alex Erickson caught a check-down pass over the middle, Core simulated blocking against two defenders before crumbling and grabbing his leg. Late indications were his foot got stepped on.

Core, a 2016 sixth-round pick out of Mississippi, had a career-high 82 yards on just four catches in the season-finale win over Baltimore to finish his rookie year and had everyone raving when he came back in terrific shape this spring. At one point the 6-3, 210-pound Core had been measured at just under 23 miles per hour last month on one route before the voluntary practices began for the fastest GPS of any Bengal until A.J. Green corked a 23 during the voluntaries.

"The playing experience Cody got last year has been very beneficial to him and everyone on the football team to be able to see his abilities," Lewis said Tuesday. "It gives him the confidence to come out and work in the offseason and know that he can achieve higher goals. He's got higher level of plays out there for him. He's got the physical tools, and I'm sure in his own mind he always believes that, but until you get your opportunity on an NFL field that you can go out there and play winning football in a game, it probably stays in the back of your mind. So it was good for him. And it's good for Andy (Dalton) to get a trust level with him. Everybody benefitted from it."

A lightning delay in the middle of practice took out a 10-minute chunk of the schedule.

KIDS SALUTE GREEN: No. 1 pick John Ross has got the scouting combine's 40-yard dash record and Cody Core was the fastest Bengal in the field phase of the off-season program, and rookie Josh Malone is here because he carried his 6-3, 209-pound frame through the 40 in less than four seconds.

But the kids are raving about the old pro. You may remember him. A guy named A.J. Green. With all the buzz about how fast the young wide receivers are, Green, the six-time Pro Bowler, quietly logged the fastest GPS time in the three weeks of voluntary practices with a route clocked at 23 miles per hour, slightly bettering Core's mark that broke 22. Throw in a couple of hellacious catches and no one has looked better than Green this spring.

"A.J.'s fast," Ross said. And on second thought he added, "A.J. can do anything."

Rookie running back Joe Mixon went as far to call Green, "Half man, half amazing." He knows the real deal when he sees it.

"Before I came here and I was a Cincinnati Bengal, I watched him and I thought he was a good receiver," Mixon said before Wednesday's mandatory workout. "But to be in the same lineup and see the way that he works … wow, he's great …He works like no other … To see him work so hard, that's what really got me intrigued. He works hard day in and day out, play after play after play. He leads by example."

Green shrugged when asked if keeping up with the kids is fueling him.

"Nah," he said. "It's what I do."