The 25-year-old had to leave the field after scoring an important equaliser for Matsatsantsa with only 10 minutes remaining on the clock to take the game into extra time, before it had to be decided on penalties.
The Tshwane side won the game 4-2 on penalties after it ended 1-1 in 120 minutes.
"Mnyamane, it's confirmed he will be out for four weeks. It's a groin strain," Tinkler told KickOff.com.
The Bafana Bafana legend, meanwhile, says central defender Clayton Daniels is fit again after struggling with cramps during extra time.
"Perfect, no issue there," he said.
Daniels gave an update on his fitness as Matsatsantsa prepare for the CAF Confederation Cup second leg semi final against Tunisian outfit Club Africain this weekend.
"I will be okay for the weekend's game. Just cramps to my calf and quad, so the muscle needs to be rubbed out then I will be okay. Nothing serious, all is good," Daniels explained.
Though the Absa Premiership matches gets underway tonight and tomorrow, the MTN8 champions will not be in action as they prepare for Sunday's all-important encounter. The first leg finished 1-1 at Lucas Moripe Stadium, so Matsatsantsa will have their work cut out in the second leg.