Amari Miller's 37th minute goal proved to be the difference in the PDL.
The victory made it four without loss in league and FA Youth Cup fixtures, seven including the Under-17s Cup.
Charlie Noakes got his first PDL appearance in the bank since early season after recovering from a broken leg.
The Under-18s Coach, Paul Robinson, said the side are in a 'really good place' at present.
"It was a really good performance.
"I thought the boys focused really well because the pitch was horrendous. That could have played on their minds - 'here we go, muddy pitch, we can't play our football . . . '.
"We spoke first about that and how we had to cope with it and the boys took everything on board. They played their good football at times but also recognised when the needed to play a bit further forward and then squeeze as a group.
"We have not highlighted that to the boys, how many games it has been (unbeaten).
"We want them to stay hungry, stay on their toes and look at the development side of it, what we are working on week in, week out and how we can then take that into a game scenario.
"Not only is it about improving as players but people as well.
"They are going to get challenges in their mind. They're going to play against different players who play differently. At the moment they are all in a really good place. It's positive to see."
Miller made his Under-23s debut in the Premier League Cup game as a substitute against Leeds United eight days previously.
Robinson said: "The goal, it was good play from Tate Campbell, through the lines. He moved the ball quickly and got it to Amari wide.
"Like we always say with Amari, when he has got someone one v one he is the best at it. He can go either left or right. He is direct, quick.
"He moved the ball half-a-yard onto his right foot and guided it nicely into the bottom corner.
"I'm really pleased with Amari. He is developing very well, listening to everything that's been asked of him and not only that we are seeing what a really good player he is."
Centre-half Noakes' return has been welcomed by Robinson.
"He played 45 minutes last Tuesday against the Pro Direct team we played in the Under-17s Cup. Then it was 60 against Crewe.
"He is progressing well. He has been a big loss. He is a winner, vocally he is very strong. He communicates very well. And he is just now building up to where he left off.
"Unfortunately he picked up a broken fibia. He was playing really well for at that time.
"But he's come through that setback and now we've got him back and beginning to see the qualities he has got which we first saw before he got injured."
Miller, Rico Patterson, with two, and a trialist with a brace were on target as Blues defeated Pro:Direct in the Under-17s Cup last week.
Blues: Clayton, Kinina, Powell, Campbell, Browne, Noakes (Djurovic 64), Sullivan, Dugmore (Chang 60), Zohore (Finnegan 83), Traore, Miller. Subs not used: Oakley, Rouse.