Assault allegation made against pro tennis player

(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, June 18th 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 didn't have any other option," he told the official ATP Tour website.

Barnes also confirmed that Nalbandian would forfeit the $56,802 prize money and the 150 ranking points he would have received. He could also face a further fine from the ATP.

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 didn'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.