The world number one was 3-2 up in a thrilling encounter when his rhythm was halted by an unwelcome guest.
Just as Selby was about to fire the white in the sixth frame, he saw an ant crawling right on top of it.
It clearly got to him and he decided to call over the umpire to investigate.
The matter was quickly rectified when the official blew the insect away and Selby was able to continue.
“It’s a little ant,” the commentator said. “You can see it just crawling along the white.
BBC
“It’s a baby ant! I think that’s a first.”
Selby is hoping to reclaim the Masters title he last won back in 2012/2013.
He recently admitted his first Masters victory is what made him a “serious, big-time player”.
“My goals are probably now more linked to the majors – win the Masters again, win the UK Championship again and, of course, win the World Championship again,” he added.”
Top 10 snooker career prize money earnings
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“Ronnie O’Sullivan equalled that Stephen Hendry record of 18 majors by winning the UK in December.
“And, like me, you know he will give it everything for another Masters title.”
Seven-time champion O’Sullivan will look to defend the championship when he faces Marco Fu on Tuesday.
The Rocket is 9-4 favourite once again to win the tournament at Alexandra Palace, while Selby is 5-1.