German police have reportedly opened an investigation into an alleged assault on Schalke 04 midfielder Kevin-Prince Boateng.

The 26-year-old was left with 'mild' injuries to his ribs, neck and back after being struck and falling onto a vase while visiting his son at his ex-wife's house on Christmas Day, according to German newspaper Bild.

Boateng is then said to have returned home following the incident before later calling the authorities.

"On Wednesday, December 25 2013, at around 12.45pm, an incident of physical assault took place in Kaarst," police in Dusseldorf told Rheinische Post. "A 26-year-old man, a resident of Meerbusch, was physically attacked on the street by a currently unidentified man.

"There are indications that the motive for the crime is connected to the personal affairs of the 26-year-old. The man was mildly injured. Criminal investigators have begun their work."

Schalke return to Bundesliga action against Hamburger SV on January 26.