The Irish play Navy at the Meadowlands on Saturday.
Floyd apparently suffered the injury in practice last Wednesday. He had nine receptions for 157 yards and three touchdowns in Notre Dame's 44-20 victory over Western Michigan in South Bend. He was schedule to go for further testing on the injured hamstring Sunday.
If Riddick can't play against Navy, freshman TJ Jones would replace Riddick as the slot receiver and John Goodman would move into Jones' starting 'X' receiver spot, Kelly said. David Toma would back up Jones and freshman Bennett Jackson would play behind Goodman.