Wilmington, Delaware:The German Tennis Federation has filed a lawsuit against the ATP in US federal court to block planned schedule changes by the men's professional tour.
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 remove 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, said he appreciated the German federation's position.
"They had a great event, a great tradition for over 100 years, and I know that they feel bad," Ljubicic said.
"But I also understand that the ATP is trying to improve our sport, and Hamburg is unfortunately one of those tournaments paying the price."
Ljubicic said players who prefer clay want Hamburg to remain a Masters Series event.
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.