Portuguese media reports say international referee Pedro Proenca was attacked late Monday in the Portuguese capital.

The Portuguese news agency Lusa says an individual struck Proenca in the head while he was in a shopping center, breaking two of his teeth.

Police reportedly arrested the aggressor, and Proenca later filed charges.

The 40-year-old Proenca refereed Porto's win over Guimaraes in the Portuguese Supercup earlier this week and last season's Champions League semifinal between Manchester United and Schalke 04.

Proenca was ranked as the No. 1 referee in the Portuguese league by the Portuguese football federation last season.