Duke held a pro day for its college basketball players Tuesday and star recruit Jayson Tatum went down with an apparent foot injury, according to ESPN.

There was no immediate word on the nature of the injury to Tatum, a 6-8 small forward with the ability to put the ball on the floor and shoot from beyond the arc. But the report suggested it "didn't look good."

Duke was ranked No. 1 in the preseason coaches poll, but they are already without fellow star recruit Harry Giles after he underwent his third knee surgery since his sophomore year in high school earlier this month. If Tatum misses time as well, Duke's depth will be tested early on.

Mike Krzyzewski said in an interview with Fox Sports that Giles experienced a setback in September from his rehabilitation from a torn ACL that cost him his senior year in high school.

“Harry is still recovering health-wise. He had just a little bit of a setback in September," Krzyzewski said. "Not structurally, but we felt he should be playing already, but they had to scope. They kind of had to clean; not the knee he hurt 11 months ago, but the other one. And it was really good.

"And so, he’s recovering even better now, and he would have never have recovered as well if they hadn’t done this procedure. So, we’re hoping that we get him (healthy).”

However, Krzyzewski did not put a timetable on Giles' return.

“I don’t want to put a time pressure on him, because I don’t think he’ll be as honest (about how he is actually feeling)," he said. "You know what a great kid he is. He just wants to play, he loves to play."

Duke returns a sensational trio of guards in Grayson Allen, Luke Kennard and Matt Jones, but losing Tatum and Giles for any length of time would be a serious blow.