United's under-18 side faced another tough test as they took on Hartlepool in a pre-season friendly, just 48 hours after playing Liverpool at their academy facility.
And they enjoyed a good first half which saw Sam Hetherington grab the lead for the Blues with a decent finish.
Pools battled to get back on terms, but the lead was restored couretsy of Dan Hill ahead of the break.
Carlisle appeared to be in cruise control but they let things slip, and Hartlepool capitalised with three goals that secured them their victory.
"We're really disappointed." youth boss Mark Birch said. "We played well and looked good, and then we let things slip badly in the second half.
"We know there's work to do, and this kind of result helps us to focus on that."