Police confirmed yesterday the unnamed 32-year-old was now well enough to be formally questioned.
An investigating judge probing the incident at Opium Beach Club in Marbella, in which four people including the Irishman were shot and the alleged gunman stabbed, will interrogate him at the Costa del Sol Hospital.
Afterwards he will decide whether to approve his release on bail pending an ongoing probe or his remand in custody.
Two people arrested earlier this week over the near-tragedy at the beach club, the suspected gunman who is a 40-year-old Dutch national and a friend suspected of aiding and abetting him, have already been remanded in custody.
The Irishman was dramatically arrested in hospital on Wednesday after leaving intensive care.
He had initially been described as a victim of a stray bullet. Detectives are said to have reached the conclusion he may have been involved in an altercation that led to the suspected gunman being stabbed and reacting by allegedly pulling out a pistol hidden in a belt bag inside his trousers and making a botched attempt to shoot his attacker.
His assailant is still being hunted by police after fleeing the VIP area on the stage where South African DJ Black Coffee was performing to a packed crowd when the drama occurred just after 1am on Monday and led to a mass stampede to reach safety.
The unnamed Irishman arrested has been identified locally as one of the "friends" that accompanied the knifeman to the sell-out event.
Respected Malaga paper Sur reported the two groups involved in the ugly confrontation in the VIP area, where tables cost up to €5,000, were Dutch on one side and “mostly British” on the other.
It also reported the suspected gunman’s pal who appeared in court on Wednesday had told a judge the row that ended with the stabbing and shooting started when the knifeman served himself a drink from a bottle on their table without permission.
The man suspected of shooting four revellers declined to answer any questions from the judge during his behind-closed-doors court appearance.
A source at the Costa del Sol hospital confirmed today the two most seriously injured gunshot victims, the Irishman and a woman who is thought to be Moroccan, were both “evolving favourably” after leaving intensive care.
A source at Spain’s National Police in Malaga said: “The third detainee at the Opium nightclub is still in hospital.
“He will be handed over to the judiciary tomorrow in hospital and a judge will decide whether to remand him in jail or release him on bail.”