Three Ajax supporters were taken to hospital before Wednesday's Champions League clash at AC Milan after being stabbed, Milan police have confirmed.
The supporters suffered injuries described as "not life threatening", but all were all admitted to San Carlo hospital due to their wounds.
A spokesman for Milan police told BBC Sport: "The one with the stomach wound is clearly the most serious but as far as I understand it's not life threatening."
One man suffered a minor knife wound during the pre-match violence near the city's Piazza Lotto but did not require hospital treatment.
According to reports in the Gazzetta dello Sport, three Ajax fans were arrested for their involvement in the scuffles.
On the pitch, Milan secured the point they needed from the goalless draw to progress to the last 16 of the Champions League at the Dutch club's expense.
Information from the Press Association was used in this report.