Aamer pulled out of his delivery stride amidst his second over with the new ball and withdrew from the field with his quota of overs completed by part-timer Cameron Delport. Karachi missed the bowling services of Aamer in that fateful encounter as they went on to lose the match in the final over.
The 29-year-old seamer has been replaced by Waqas Maqsood, who has previously turned out for Islamabad United.
The replacement was finalized following approval from the event's technical committee comprising of PCB CEO Wasim Khan, Bazid Khan, Marina Iqbal, Sameer Khosa and Dr. Sohail Saleem.
Waqas earned his solitary Pakistan cap in 2018 when he played against New Zealand in a T20I in Dubai.
Aamer's late introduction in the tournament provided Karachi with added depth in their bowling department. His miserly economy rate of 5.87 across three games this season cushioned the attack from being punished.
While Waqas has been brought into the side, it is likely that the Kings will persist with Umaid Asif in Aamer's place.
Karachi's next match will be against archrivals Lahore Qalandars at the National Stadium on Thursday. They are currently placed fifth on the six-team table.