Mako, 32, looks set to miss the start of the 2026/27 campaign after sustaining the injury in the 1-1 draw with Saudi Arabian club Al Kholood on Tuesday.
“Mako has returned to South Africa for medical care and will consult a specialist orthopaedic surgeon for further assessment. He is expected to rejoin his teammates in the coming weeks once his recovery is under way,” Chiefs said in a statement on Friday.
The former Orlando Pirates left-back made 18 appearances, including 12 starts, for Chiefs in his maiden season at the club after making the switch across Soweto.
He had spent the previous seven campaigns at Pirates after joining them from Chippa United in 2018.
Chiefs will need the full breadth of their squad as they compete across multiple fronts this season, including in the CAF Confederation Cup.