Nevertheless, Dieter Keller beat many greats of his time: Robert James Fischer, Bent Larsen, Efim Geller, Jan Hein Donner, Arturo Pomar, Jonathan Penrose, or mentioned Oscar Panno.
Despite being outperformed by many top players of his time, Dieter Keller still managed to beat notable figures such as Robert James Fischer, Bent Larsen, Efim Geller, Jan Hein Donner, Arturo Pomar, Jonathan Penrose, and even the skilled Oscar Panno.