Vikings cornerback Captain Munnerlyn was sidelined from Thursday's practice with a walking boot on his right foot, an injury he said would not threaten him come training camp in July.
Munnerlyn is fighting to retain his starting left corner job after the Vikings signed 12-year veteran Terence Newman and drafted Trae Waynes 11th overall out of Michigan State.
He initially injured his foot last week at the start of organized team activities but continued practicing on it.
"Then come Monday, I couldn't run," he said. "I was like, 'Oh, man, what's going on?' Got an MRI, got a little something going on.