One of the pair distracted the victim, while the second thief stole the backpack, according to police spokesman Thomas Keiblinger.
The Japanese student noticed the theft, and began to struggle with one of the two men, who both fled, reported the Austrian Press Association on Sunday.
The student then gave chase and followed the duo at a dead run. He was able to catch one of the suspects at the corner of Mariahilferstraße and Zwölfergasse. Unfortunately, the thief pulled a knife, and stabbed him in the neck and shoulder, then ran off.
Several passers-by rushed to the victim's assistance, while the assailants fled.
The victim has been taken to hospital, where he is being treated for stab wounds in his neck, left shoulder-blade and on the fingers of his left hand.
Police are appealing for any witnesses who might be able to help them to trace the perpetrators.