High Quality Content by WIKIPEDIA articles! The German Open Hamburg, established in 1892, is an annual tennis tournament for male professional players held in Hamburg, Germany and part of the Association of Tennis Professionals (ATP) Tour. Originally a Grand Prix Tennis Tour event between 1978 and 1989 it was part of the Grand Prix Championship Series. The tournament is played on clay courts at the tennis center Am Rothenbaum. In the past, it was contested in May, as a precursor to the French Open. Currently, it is held in July instead.