The World Championship finalist played his quarter-final victory over Stuart Bingham at the same time as Brecel was taking world no.4 Murphy into a deciding frame.
But between points Carter revealed he found himself watching as Brecel held a lead over 2005 world champion Murphy, only to miss out at the last.
Carter, whose own victory over in-form Bingham by 6-4 was far from routine, now faces Murphy for a place in the final at York having revealed he was relishing the prospect of a match-up with 17-year-old Brecel.
"When Luca looked like winning I thought 'this is a good chance for me if I can win, and then I have got Luca'," he said.
"I would go into that as the bookies favourite, though anything can happen and no-one is to be taken lightly in a UK Championship semi-final.
"Luca has got great temperament, I see him miss a few balls or get a few kicks and he is just smiling as if he is having a walk in the park or playing with his football.
"He looks like he is in a good place and he is obviously going to do well."
Of his own form, 33-year-old Carter believes there is more to come.
He said: "I don't feel like I have played particularly great but I'm in the semi-finals and I will take that.
"I have had some battles with Shaun in the past and he is a great player."
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