Spaniard Mari, currently on loan at Italian Serie A side Monza, had surgery on Friday after being stabbed in the back.
He's expected to return to training in two months, a medical report said.
"The operation went well and he is expected to be discharged in two or three days," the medical report said.
"After the operation, the player will be able to start a rehabilitation process. This type of muscle injury usually requires two months of rest before being able to resume physical activity."
Mari was injured after allegedly being attacked on Thursday by a 46-year-old Italian man who reportedly suffered from mental health problems.
He allegedly stabbed four other people, one of whom - a Bolivian male employee of the Carrefour supermarket - died on the way to hospital.
According to Monza CEO Adriano Galliani, who visited the player in hospital on Thursday night, revealed the Spanish defender, who has played for clubs in five countries, admitted "he was lucky" to have survived because he saw a person die in front of him.
The attack occurred on Thursday evening, when the man allegedly grabbed a knife from the supermarket shelves and began stabbing people in the vicinity, including the player who was with his wife and son.