WILMINGTON, Del. -- The German Tennis Federation has filed a lawsuit against the ATP in federal court to protest planned schedule changes by the governing organization for men's tennis.
The German federation said Friday that months of negotiations between the two sides had broken down over a plan by the ATP to reduce the clay-court Masters tournaments -- leading up to June's French Open -- to Madrid and Rome, starting in 2009.
That would bump the Hamburg Masters from its traditional spot on the calendar and take away its status as a major clay-court warmup for the Roland Garros Grand Slam.
The federation filed suit Wednesday in U.S. District Court in Wilmington, saying a contract guarantees Hamburg's spot on the calendar.
"The structural changes planned by the ATP will clearly hurt Hamburg the most," federation president Georg von Waldenfels said. "As a result there would be major economic disadvantages to us."
German media reported 60 players -- including Roger Federer and Rafael Nadal -- signed a petition against the move.
Croatia's Ivan Ljubicic, head of the tennis player's union, told German news agency DPA that members were disappointed with the change and that Hamburg had a long tradition and high attendance.
The ATP stood by its plan.
"The ATP is confident in its position and will continue to take steps to improve and grow its men's professional tennis circuit for the benefit of fans," the organization said in a statement.
Tommy Robredo of Spain won the Hamburg Masters in 2006.