The 30-year-old celebrated New Year with friends in Skärblacka outside Norrköping and got into a fight with a now 23-year-old man outside Folkets Hus at twelve o'clock.
The 30-year-old drew a knife and stabbed the victim in the left side of the back with a so-called mora knife.
The 23-year-old was able to leave the scene and called 112. He did not understand at first that he had been stabbed and received no injuries to internal organs.
But according to the forensic examination, the damage that occurred to the lung sac is judged to have been life-threatening.
The 30-year-old has been punished before and has admitted the circumstances on New Year's Eve.