An 18-year-old Derby man is recovering in hospital after suffering head injuries in an attack in the city centre.
The man was walking near Wardwick in the early hours of Saturday when he was hit in the face.
He fell to the ground and cut his head open. He was taken to Royal Derby Hospital but later transferred to Nottingham's Queen's Medical Centre.
Police have appealed for witnesses to the "unprovoked" attack.
The attacker is described as aged between 20 and 23, about 6ft 1in tall and was wearing a dark T-shirt with blue jeans.
He was with another man wearing a red leather jacket with jeans.