Officers have questioned a 24-year-old man from Fareham in connection with the attack, which took place in Lynton Grove, Copnor, on Saturday evening.
Police said the man was arrested on suspicion of causing grievously bodily harm with intent. but has since been released without charge – although a spokeswoman for Hampshire Constabulary said he would ‘remain under investigation’.
As previously reported, the 31-year-old victim from Portsmouth was stabbed twice during a violent attack between 10.30pm and 10.50pm on Saturday.
Witnesses said he collapsed at the junction of Tangier Road and Lynton Grove, after leaving a bloody trail along the street.
The victim was treated at the scene by paramedics before being taken to Queen Alexandra Hospital where he remains.
It is understood his injuries are serious but not thought to be life-threatening.
The violence is thought to have sparked following an altercation inside the Co-Operative, in Tangier Road.
Men were heard arguing in the store, before the row spilled out into Tangier Road and then escalated in Lynton Grove, where the victim was stabbed.
Rachel Jenkins, 47, of Lynton Grove, was woken by the noise and said she was horrified by what had happened.
She said: ‘My son, Jake, came home and said he saw the bloke lying in a pool of blood, with paramedics and ambulances everywhere.
‘When he said that I just felt sick.
‘I moved from London to get away from knife crime and now it’s on my doorstep.’
Yesterday forensic officers in white overalls were combing the street for clues.
Officers have since appealed for the public’s help in providing any CCTV footage or dash-cam footage.
A spokesman for Hampshire Police added: ‘Anyone who saw or heard any of the assault or what led to it, is asked to contact the Eastern Investigation Team on 101 and quote crime number 44190136697.
‘Alternatively Crimestoppers can also be contacted anonymously on 0800 555 111.'