Collingwood will miss the event due to a buttock injury he picked up during the just-concluded ICC Champions Trophy in South Africa.
Retired from international cricket, McGrath will come into the tournament with little match practice as he had warmed the bench during the second edition of the Indian Premier League (IPL) in South Africa.
Meanwhile, the event's technical committee also allowed South African side Cape Cobras to replace their injured player Richard Levi with Stiaan van Zyl.
Levi is nursing a hand injury he sustained during training in Bangalore this week.