The MMA icon is a follower of heavyweight sides in England and Scotland, with the Irishman prepared to start pumping some of his personal fortune into ventures outside the octagon.
He was among the first to raise his hand when Red Devils supporters stepped up their protests against the Glazer family at Old Trafford, while talks have been held regarding a possible stake in Scottish Premiership giants at Parkhead.
McGregor was asked during a Q&A session on Twitter whether he will be buying into United, with the 32-year-old saying: “A conversation came up regarding Celtic first to be honest. To acquire shares from Dermot Desmond. I am certainly interested in acquiring a sports team at some stage!
“Both Celtic and Man United are teams I like for sure, but I am open. I feel I could do big things for a club.”
The Irish financier is the largest stakeholder at Celtic. He has selected most of the managers at Parkhead since Martin O’Neill took charge back in 2000.
Plenty of success has been enjoyed during his time at the helm, but the Scottish Premiership title has been ripped away by Old Firm rivals Rangers in 2020-21.
McGregor first took to social media to hint at interest in getting involved with the Red Devils on April 21.
Those comments were made amid the fallout from the Super League proposals, from which United eventually withdrew following a fierce backlash against all of those involved, with pressure being put on the Glazers to sell up.
McGregor could form part of any takeover talks, having stated in the past regarding his allegiance in football circles: “I was more a player than a watcher back then, but Manchester United was my team.
“It was only the other day I came across an old picture of myself wearing that infamous grey United jersey, which I bought with my [First Holy] Communion money at eight years of age.
“I see my son when I look at that photo. I’d love to know where it is now. A truly ‘Notorious’ football jersey!”