In the first incident, a student was taken to hospital after he was punched in the head by someone in a group of men outside the Night n' Day store on George St about 2am.
The victim's condition was unknown yesterday, but police were following a lead on a vehicle connected to the group.
About 3.45am, a group of five males and one female attacked a group of four students on the corner of the Lower Octagon and George St.
Senior Sergeant Steve Aitken said the students were on their way home and were "play fighting", when the other group attacked them.
One of the students fell unconscious after he was put in a sleeper hold and another was knocked out when he was punched in the stomach.
Both victims refused medical care.
The offending group headed towards the Hoyts cinemas.
The incident was caught on CCTV, but police would also like to hear from any other witnesses or information.
Earlier in the night, police charged a 29-year-old Dunedin man after a short pursuit in central Dunedin.
The man was pursued around the block at 12.30am after he failed to stop for police, who noticed the car he was driving leaving the BP Cumberland St without its headlights on.
Police said when he pulled over he was found to have 861mcg alcohol per litre of breath, more than twice the legal limit.
He faces charges of failing to stop, dangerous driving, and driving while disqualified.
Police are also investigating a burglary at a Castle St flat at 1.45am.
Snr Sgt Aitken said it was reported a female occupant of the house got out of bed after hearing someone trying her locked bedroom door.
She found the living room ranch slider open and a laptop missing.
