United's under-18 game against Gretna, scheduled for a 3pm kick off on Saturday 6 July, has been cancelled following talks between the clubs today.
Youth boss Eric Kinder explained: "I've spoken to the staff at Gretna, and I've apologised to them, but they were fantastic and I think they understand the reasons why I've had to make this call.
"I just feel that it's come a little bit too soon in our pre-season schedule, particularly with us having games coming up next Tuesday and the following Saturday.
"We have to bear in mind that we have a group of first year scholars who are getting used to training at this level of intensity. We're seeing some of them start to feel one or two little niggles, and what I don't want to do is create a risk of them picking up injuries when their bodies are still getting used to full-time football.
"We also have a situation where the manager is going to use four or five of the second year group in his training sessions. That would have meant that I'd have been calling on under-16s to fill those spaces, and that age group hasn't started training yet following their summer break.
"One of the things I spoke to Gretna about was that I didn't feel, due to this set of circumstances, that they'd get much out of the game at all. Like I say, I've apologised, and I do think they understand the thought process we've been through."
Friendly: Morecambe v United - Morecambe and Lancaster College - Tuesday 9 July, 12pm