It was a decision that had fans and pundits alike baffled as the Reds struggled notably to contain the threat of Newcastle’s towering defender from corners in the first half at Wembley.
And Liverpool paid the price for those failings on the stroke of half-time when Mac Allister backed off Burn, who built up a head of steam before connecting with Kieran Trippier’s delivery from the left and powering an emphatic header low and beyond Caoimhin Kelleher at the back post.
That gave Newcastle a deserved half-time lead, with Alexander Isak then scoring a second after the break quickly after seeing a close-range effort ruled out for offside against captain Bruno Guimaraes.
Reds boss Slot was inevitably quizzed after a hugely underwhelming final performance on why it was left up to midfielder Mac Allister to try and stop the significant set-piece danger posed by Burn, despite the considerable height difference between the pair.
“Again, credit to Newcastle. But I can explain,” he said at his post-match press conference. “We play zonal so we have five players zonally close to our goal, so if the ball falls there it is always one of the five stronger players that are going to attack that ball. And we have three players that man-mark and Macca is one of them.
“Normally a player like Dan Burn or another one runs to the zone because normally… I think he’s an exception to that because I have never seen in my life a player from that far away heading a ball with so much force into the far corner.
“That is part of logic, that they either have to go far away from our zone, which 99 out of 100 times that will never lead to a goal, or they have to arrive in our zone and then it’s an equal battle, if you want to call it like this.
“So credit to him, I think he’s one of the few players that can score a goal from that distance with his head.”