Head coach John Mitchell has been suspended by the struggling Lions with immediate effect.
There had been reports of a players' revolt against the New Zealander - and the club have now acted after they received a "list of grievances".
"The nature of the complaints is so serious that we have suspended him pending further investigation," GLRU president Kevin de Klerk told Rugby365.
Mitchell had led the side to their first Currie Cup title since 1999 last season but the Lions have continued to struggle in the Super Rugby competition.
They are bottom of the South African Conference and 14th overall - with the side in danger of losing their place to the Southern Kings franchise.