Shortly after 1pm on Thursday 2 January 2014, a silver or grey Peugeot 406 estate was in collision with a 63-year-old man on Hill Street near the junction with Wellington Street West.
The man initially walked home but later collapsed. He was taken to Salford Royal Hospital with a serious head injury and remains in a critical condition.
The driver of the car did not stop.
Police are appealing for witnesses and information and are seeking the driver.
Police Sergeant Paul Higgins from the Serious Collision Investigation Unit said: “We are actively searching for the driver involved in this collision. I would appeal directly to that driver to contact us immediately and tell us what happened.
“We are working hard to trace the vehicle involved and the person driving at the time but would ask if anyone knows of someone who may have been driving such a vehicle in the area around the time of the collision that they get in touch as soon as possible.
“I would urge anyone who witnessed the collision, events before or after it, or who has any information about the driver to get in contact.”
Anyone with information should call the Serious Collision Investigation Unit on 0161 856 4745 or the independent charity Crimestoppers anonymously on 0800 555 111.