Dutchman Gerco Schröder rises to second behind Ahlmann, thanks in part to his team's victory in the Nations Cup, while Frenchman Kevin Staut drops to fourth from second.
Splitting that pair is American Beezie Madden who along with Australia's Edwina Tops-Alexander are the sole female representatives in the top 10.
In the latest dressage rankings, there is no change to the top six, with Adelinde Cornelissen, Helen Langehanenberg, Charlotte Dujardin occupying the top three spots.
The first change comes in seventh place, where Patrick Kittel displaces Italian Valentina Truppa.
As for eventing, New Zealander Andrew Nicholson still tops the rankings, while his compatriot Jonathan Paget takes third place from Germany's Michael Jung.
More significant changes are found a little further down the ladder where Britain's Marilyn Little climbs to sixth from 16th and her compatriot Oliver Townend rises to seventh from 13th.
But the most impressive rise this month is that of young Frenchman Astier Nicolas who climbs from 32nd to 8th.