Beerbaum, a son of Baloubet du Rouet, won the ninth leg of the Global Champions Tour as he hit back at his critics after missing out on selection for the London Olympic Games.
The German imposed himself as he fought off five other opponents who had cleared the first round.
A Grand Prix that was ridden in blistering heat which probably came as a shock for horses like Itôt du Château, Edwina Tops-Alexander’s favourite.
The brave chesnut, who was on home soil, conceded three faults towards the end of the course, which was very unusual for him.
Edwina Tops-Alexander is still in the lead in the overall classification with
189 pts with Christian Ahlmann, on Taloubet Z, now just behind on 169 pts.
The next legs are held in Lausanne (14-16 September), Vienna (20-23 September) and Abu Dhabi (22-24 November) promise to be decisive.