The winger came in for some stick from seconds of the City support who travelled to Oakwell but was in the right place to score and send City to the top of the Championship.
Said Chris Coleman to the CT: "It was a great finish and I was delighted for Julian because I always had it in mind to change both wingers, him and Michael Mifsud, in the second half.
"I said to the players 'look, we've got a bench full of forwards so give us what you've got and if you blow up with 20 minutes to go we'll make changes.'
"Julian and Michael did a terrific job for us defensively - our shape was much better today - and I thought it was great for Julian to get the winner and receive a standing ovation from our fans as he came off the pitch.
Julian Gray scoring at Kilmarnock
"To be fair, I don't think the fans were booing him so much as singing for Leon because The Duke is a very popular player."