The division between players who jumped ship to LIV Golf and those who stayed the course has been well documented, but personal interactions between players have remained somewhat cordial.
However, tensions seem to have reached boiling point between some. Spanish news outlet TenGolf.com reports that Reed and McIlroy were on the range at the Emirates Golf Club on Tuesday ahead of this week's Dubai Desert Classic.
Reed, who joined the LIV Golf wantaways but remains eligible to play DP World Tour events - for now - reportedly walked up to McIlroy and his caddy Harry Diamond, exchanging greetings with the latter.
But turning his attention to McIlroy, who was on his haunches at the time, there was no such reciprocation. When it was clear he was being ignored, Reed turned on his heels and chucked a tee at McIlroy in disgust.
The world number one has made no bones about how he feels toward the breakaway league.
"I hate what it's doing to the game of golf...I hate it," said McIlroy at Wentworth before the BMW PGA Championship in September.
"Like it's going to be hard for me to stomach going to Wentworth in a couple of weeks' time and seeing 18 of them there. That just doesn't sit right with me.
"So yeah, I feel strongly. I believe what I'm saying are the right things, and I think when you believe that what you're saying is the right things, you're happy to stick your neck out on the line."