ALLEN PARK, Mich. -- Detroit Lions cornerback Darius Slay missed Thursday's open OTA practice due to what his coach, Jim Caldwell, described as "self-inflicted" bruises on both of his hands.

Slay, who is arguably the team's top cornerback, attended practice and had his hands wrapped. He participated in some noncontact drills without a helmet and shadowed the team's other starting cornerback, Rashean Mathis, in others.

"Got a few bruises that were self-inflicted," Caldwell said, "but nevertheless, he's out for a couple of days."

Caldwell wouldn't explain what Slay did to cause the self-inflicted injuries. Slay did not talk with the media following Thursday's practice.

A message left by ESPN for Slay's agent, Eugene Parker, was not immediately returned.

"It happened," Caldwell said. "Just kind of an odd [thing]."

Slay had 60 tackles and two interceptions last season for Detroit in his first year as a full-time starter at the position.