Giggs has never played against Cardiff in his 22-year career and is set to face his 117th club playing for United when they travel to the Bluebirds at the weekend.
Mackay said: "He is a top bloke and he is probably my favourite player of the last 15 years.
"I met him a couple of weeks ago at the FA Pro Licence course I was talking at, and he is now stepping into the other side of the game in that player-coach role I had at one point and a lot of players have had at some point when their careers are finishing.
"But I think you look at how he has conducted himself professionally through his whole career and he just looks a model pro.
"The way he has kept his body and how his game changed when his pace went, and his thought process in terms of how to play.
"Even the way he started to adapt his body through using yoga to allow him to play into his 40s, he has been an absolute star and he is obviously an iconic figure here for what he has done for Wales and I have no doubt at one point he will end up in management.
"He has learned from the best (Sir Alex Ferguson) and it will be good to see him on Sunday."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball