Officers who were called to a collision in Elm Grove at 1.40am on 26 April are now treating the incident as an assault and are appealing for witnesses.
A 36-year-old man was taken to Queen Alexandra Hospital following the collision with a car, described as a Ford-focus style, which failed to stop at the scene.
A 42-year-old man from Southsea was arrested on suspicion of grievous bodily harm with intent. He has been released from custody, but remains under investigation.
We’d like to hear from anyone who witnessed the incident.
If you have any information relating to this case, please call 101 quoting reference ‘44180153171’, or contact Crimestoppers anonymously.