Mackay, a former Scotland international, guided Cardiff to the Championship title in 2013 before being fired barely six months later by controversial chairman Vincent Tan.
He has since been unemployed, and was immediately linked with the Eagles job upon Pulis's decision to walk away from Selhurst Park - not least due to his close relationship with Palace's Sporting Director Iain Moody, who was one of Mackay's key liutenants at Cardiff.
Pulis asked to leave Palace 48 hours before the start of the new Premier League campaign, reportedly after becoming frustrated at the club's failure to land summer transfer targets.
A number of names had been thrown into the hat as to whom would succeed the former Stoke City manager, with ex-Tottenham Hotspur boss Tim Sherwood widely tipped and Glenn Hoddle reportedly making an official application for the vacancy.
Sherwood was soon installed as the bookies' favourite and at one point on Tuesday betting was suspended on him being named as the new Eagles boss, but it is believed that disagreements over backroom staff led to the sacked Spurs man missing out. Mackay is now widely reported to be unveiled in the next few hours.
Mackay will now be faced with the task of securing Palace's top flight status following an opening day defeat to Arsenal.
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