The forward is understood to have had surgery shortly after the end of the previous campaign and did not travel with the Amakhosi squad to Spain for their pre-season tour under new coach Fernando Da Cruz.
With the Glamour Boys enjoying their best campaign in seven years under the previous technical team of Cedric Kaze and Khalil Ben Youssef – finishing the Betway Premiership in third place – Mayo had played some part of it.
The forward managed 15 matches in all competitions and scored two goals, the reason for the low return being put down to his return to the Premier Soccer League as well as injuries over the course of the season.
Mayo initially joined Chiefs on loan from Algerian side CR Belouizdad in September last year before the Soweto giants exercised the option to sign him permanently.
However, the start of his first full season as a permanent Chiefs player has been delayed, with information gathered by the public broadcaster indicating he is only expected to return to full training over the next two months.
The former Cape Town City striker endured a stop-start debut campaign at Naturena, with injuries limiting both his appearances and consistency.
As a result, Mayo is likely to miss Chiefs' MTN8 clash against Golden Arrows as well as the opening rounds of the Betway Premiership while continuing his rehabilitation.
The 27 -year-old is now targeting a return in September – presumably after the FIFA international break – when he hopes to begin competing for a regular place under Da Cruz as the Frenchman begins a new era at Naturena.
For now, Mayo will continue his recovery programme while Chiefs prepare for the new season without one of their attacking options.