A man left with serious head injuries after a possible hit-and-run has been identified.

The 44-year-old man remains in a critical condition in Christchurch Hospital after he was found by a walker in a driveway on Yaldhurst Road near Riccarton racecourse around 6.30am on Wednesday.

Police have been examining the man's home, not far from where he was found, to try to piece together his movements.

The man is described as caucasian, about 170cm tall, of medium build, with short red hair, a goatee and tattoos.

"We would like to hear from anyone who has seen this man, or any unusual activity, in the vicinity of Yaldhurst Road and Racecourse Road, overnight or this morning," Detective Senior Sergeant Tony Hill said.

Police have already received several calls from members of the public who have passed on helpful information, he said.