( CNN ) -- David Nalbandian is under police investigation for an alleged assault after a line judge was injured when the Argentine tennis star kicked over an advertising board in Sunday 's Queen 's Club final . London 's Metropolitan Police confirmed to CNN Monday that a complaint had been received following the incident , which led to Nalbandian 's disqualification , with Croatian Marin Cilic awarded the title . `` We are aware of an incident which took place at the Aegon Championships on June 17 , '' said a police spokesman . `` A complaint of assault has been made and the Metropolitan Police Service is now investigating . '' Nalbandian was a set up , but trailing in the second when his frustrations boiled over after failing to return a Cilic service . He lashed out at a court side advertising board , behind which line judge Andrew McDougall was sitting . The force of the kick dislodged the display , which hit McDougall and left him a nasty gash to his left leg . McDougall was seen to angrily remonstrate with Nalbandian , who was defaulted for `` unsportsmanlike conduct . '' ATP supervisor Tom Barnes confirmed that he had been left with no other choice , much to the disappointment of a capacity crowd who had been enjoying a closely contested final . `` Once I saw the injury it was not a judgment call . I did n't have any other option , '' he told the official ATP Tour website . Nalbandian forfeited the $ 56,802 prize money and the 150 ranking points he would have received and later Monday was fined $ 12,564 by the ATP for his actions . Nalbandian , who was defaulted for insulting a linesman at tournament in Chile in 2002 , said he regretted the latest incident . `` I made a mistake and I apologize , '' the 30-year-old told the official ATP Tour website . `` I feel very sorry to the guy . I did n't want to do that . This is a bad situation for everybody that I really apologize for . '' The official tournament website said McDougall had been tended to by St John 's Ambulance and ATP medical staff but did not need any further treatment .
London 's Metropolitan Police to investigate assault allegation against David Nalbandian . Nalbandian injured line judge after kicking over an advertising board . Nalbandian loses his $ 56,802 prize money and ranking points from Queen 's Club event . NEW : Argentina star fined 10,000 euros ( $ 12 , 564 ) by the ATP .