“Andre Wisdom was the victim of an unprovoked attack and robbery,” the Derby statement said.
“He suffered injuries due to which he was admitted to the hospital, where he is in a stable condition.
“Merseyside police are investigating and the club will focus its efforts on supporting Andre and his family.”
Merseyside police did not immediately respond to CNN Sport’s request for comment.
Wisdom played in a 2-1 derby against Reading on Saturday.
He signed for the Liverpool club after a series of spells on loan and has made 20 appearances so far this season.
The derby has an outside chance of qualifying for the championship play-offs as the club seeks promotion to the English Premier League.