Officers are investigating an incident whereby a 21-year-old man from Portsmouth was assaulted on Stanhope Road at 5am on Sunday 23 January.
It was reported two men approached another group of men and assaulted one of them.
The 21-year-old man who was assaulted suffered an injury to his face and attended hospital for treatment.
The two men who had approached the group reportedly left the scene in a van.
It is believed one of the men was carrying a weapon.
Officers investigating the assault arrested both a 51-year-old man and a 35-year-old man on suspicion of causing grievous bodily harm with intent and possession of offensive weapon in a public place.
They were questioned by officers and released under investigation while enquiries to continue.
Officers investigating the assault would like to hear from anyone who may have seen the incident take place, or saw a man in the area carrying a weapon in the early hours of Sunday morning.
Anyone with information is asked to call 101 and quote 44220030038.