Soccer professional Pablo Mari from the Italian first division club Monza Calcio has to be operated on after the knife attack in a Milan shopping center.
Because of stab wounds in the abdomen and on the back, an operation was necessary, according to the Niguarda Municipal Clinic.
The 29-year-old was one of six injured in the knife attack, for which a mentally disturbed 46-year-old Italian is blamed.
A cashier from Bolivia died in the attack.
"Pablo says he was lucky," reported Monza Managing Director Adriano Galliani after a visit to the clinic.
The knife did not injure any important organs.
Arsenal previously tweeted that Spaniard was doing well under the circumstances after he was taken to hospital by helicopter.
The attacker was arrested by the Carabinieri after Massimo Tarantino (51), a former Inter Milan player, is said to have disarmed him along with other customers of the shopping center.
According to the first findings, the investigators ruled out a terrorist background.
The alleged perpetrator was being treated for depression and mental disorders.
AC Monza chief executive Adriano Galliani tweeted: "Dear Pablo, we are all close to you and your family, we love you.
Keep fighting as you can, you are a warrior and you will recover soon.” Serie A President Lorenzo Casini expressed his solidarity with the Monza pro and sent condolences to the families of the killed supermarket worker.
A young woman told the Ansa news agency that people in the supermarket were very afraid.
"We saw people running away crying." Another girl said it was initially thought it was a robbery.
"Then we started seeing more and more people with shocked faces and we realized something serious had happened."
Mari has been at Arsenal since 2020 but was loaned out to Udinese Calcio in Italy last January.
He briefly returned to England in the summer before moving back to Serie A on loan, this time to Monza.
The Lombardy club is owned by former Italian Prime Minister Silvio Berlusconi.