The Argentinian kicked an advertising board in a fit of anger after missing a shot. A piece of the platform hit the line judge in the leg. He was treated for a bloody shin.
Nalbandian was disqualified for unsportsmanlike conduct. He was actually winning the match against Marin Cilic during the Queen's Club final.
London police said they're investigating a complaint of assault filed against Nalbandian. Authorities declined to say who made the complaint. 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.
Nalbandian won the first set 7-6 (3) but lost his temper after losing serve to fall behind 3-4 in the second. After missing a running forehand on game point, he kicked the board under the chair of line judge Andrew McDougall. A piece of the board cut the judge on the left shin, leaving him bloodied from an inch-long gash.
ATP rules state that any violent action will result in an automatic default. However, Nalbandian insisted he shouldn't have been disqualified.
The Associated Press contributed to this report.