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.
Dieter Keller excelled over several prominent players of his generation: Robert James Fischer, Bent Larsen, Efim Geller, Jan Hein Donner, Arturo Pomar, Jonathan Penrose, or even the skilled Oscar Panno.