LONDON (AP) Police are investigating an assault complaint filed against David Nalbandian after the Argentine tennis player kicked an advertising board and injured a line judge during the Queen’s Club final.

London police declined to say who made the complaint against Nalbandian, who was defaulted from Sunday’s match against Marin Cilic in the grass-court Wimbledon warmup event.

Any member of the public who witnessed the event in person or on television could have made a complaint, as could the line judge himself.

”We are aware of an incident at the Aegon Championships,” the Metropolitan Police said in a statement on Monday. ”A complaint has been made and the Metropolitan Police Service is now investigating. The allegation is of assault.”