It is understood that during the incident he suffered at least one stab injury.
The Ambulance Service said one of its crews responded to a report of a possible stabbing at Dunluce Avenue around 6.40 am this morning.
Paramedics treated one man at the scene who was in a serious condition and took him to the accident and emergency department at the Royal Victoria Hospital.
A PSNI spokeswoman said the road has been closed to traffic and diversions are in place.
However, pedestrian access will be permitted to Dunluce Health Centre.
There are no further details at present.