The Daily Star says Mackay is poised to sign a three-year contract to replace Tony Pulis at Selhurst Park.
Mackay wants to bring former Eagles favourite Zaha back to Selhurst Park from United.
Zaha has been frozen out at Old Trafford and is free to leave the club, with Palace one of a number of clubs looking at him.
Eagles chairman Steve Parish is a massive fan and it was a disagreement over Zaha which caused Pulis to dramatically quit last week.
The former Stoke boss was not keen on a move for the 21-year-old and questioned his character.
But Mackay has no such reservations and is ready to move fast when he is confirmed in the Eagles hotseat.
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