The visitors scored from a set-piece 20 minutes into the game at a windswept Trillion Trophy Training Centre, Wast Hills, and try as they might, Blues couldn't find a way through.
Remi Walker and Adan George both had decent attempts that were repelled, but Blues were left 'frustrated', commented coach Paul Robinson.
"I thought we started a bit sloppy, gave Leeds some momentum into the game. Safe passes, not wanting play forward a lot. Encouraged the pressure, which Leeds are very good at.
"We conceded the goal from a set-piece. Was it lined up properly . . . ? You could argue a few things there with the boys and taking control of the situation.
"We had a lot of possession but comfortable possession, that didn't really hurt them. We needed to move the ball quicker, from side to side and get in.
"Second-half it was totally different. We were on the front foot all of the time and created numerous chances. But did we really test the 'keeper with the wind with us? Not really.
We had two or three shots when we could have got a lot more off on target."
Yoane Zohore was a menace for Blues and Robinson said: "He did well up front. He was a problem for them. He played off the shoulder, held the ball up well and linked play with those joining in. He was the standout one for me.
"For most of the lads it was standard sixes (out of 10). A few below par but it is understandable at times, in this weather and conditions.
"But the boys have to understand they have to play in any conditions. It doesn't matter what it is."
Zohore has had a steep learning curve since coming into full-time football this season as an Academy Scholar.
Robinson said: "With Yohane, he just needs coaching. From France, he has never been in the system before. It is all brand new for him. You have got to take more time with him.
"We have sat down, we have had conversations over his clips about where he should be positionally and also we've worked with him on the training pitch about holding the ball up better and spinning to get into the box to then score goals.
"We are getting there. He's still only 17. I know everyone looks at him and he's a unit. He's still a baby in football terms. He's still understanding the Club and as coaches how we want him to play.
"I've been pleased with him but it will take time. We will continue to work with him so we get him firing and scoring goals."
Blues get the chance to bounce back immediately as they face Bolton Wanderers Under-18s at home on Tuesday in the league.
"We have got a few of the younger lads with us, which is good for me to get a look at them," said Robinson.
"Again, it is a test for the boys now. They have just lost at the weekend, so what do they want to do about it?
"We've had an analysis meeting and recapped a few things that we need to be better on, so it's about them now. How can they make the difference? We are hoping to see a reaction."
Blues: Clayton, Oakley, Djurovic, Chang, Browne, Noakes, Miller, Dugmore, Zohore, Finnegan (Walker 60), George. Subs not used: Rouse, Sullivan, Hamilton, Nguepissi.