The German dressage metropolis held the European Championships last year and the annual competitions in April open the outdoor season for many crews.
Sweden has strong representation in place with seven crews in the three- and four-star classes.
In today's opening Grand Prix, Ramel and Buriel got 76.261 percent and placed ahead of national team mates Therese Nilshagen / Dante Weltino and Patrik Kittel / Touchdown.
Nilshagen came fourth at 75,652 and Kittel fifth at 75,609.
The three crews are all highly relevant for the national team captain Bo Jenås' team for the World Cup in Herning in August.
German Isabell Werth won at Quantaz with a percentage of 77,957.