The Steelmen boss has seen a number of players leave Fir Park during the close season and with money tight, he has little scope for bringing new faces to Lanarkshire as they attempt to land a berth in the Champions League while prospering in the SPL.
Midfield starlet Steven Hetherington turned in an impressive display during Well's 1-1 draw with Raith Rovers on Tuesday night, with Josh Watt, Lee Erwin, Craig Moore and Euan Murray also steeping up.
And McCall has called on the best of his Fir Park apprentices to prove they have what it takes to make it in the Fir Park first-team.
He said: "I like Steven (Hetherington). He has got a great attitude to the game. One or two could have done a bit better, but they are bedding in.
"They have got to come in. We have lost 10 first team squad members over the close season and we have brought five of the Under-19s up.
"When called upon, they are going to have to do it. Nineteen and 20 is not young any more. If you are going to be good enough then you should be ready at that age.
"I am sure that is going to be the case with a lot of SPL clubs. We are going to have to blood a few more youngsters and give them the chance.
"The only reason a lot of them didn't get a go last season was because the squad was so consistent and we were injury free fortunately.
"I am sure this year they will get a chance sooner or later. I thought Steven did very well on Tuesday."
Well fans have the chance to see former hero James McFadden in claret and amber this weekend when he stars in Stevie Hammell's testimonial match with Everton.
The striker, who still enjoys legendary status with supporters, has been training with Well after leaving the Toffees in the summer.
He is keen to find a new club and has not ruled out a switch to Celtic.
McFadden said: "It is something that would appeal to me but whether it is a possibility, I don't know, you would need to ask somebody at Celtic.
"I don't want to go into it (previous link with Celtic). There was a wee bit of a mix-up.
"But if anybody comes to speak to me, I will speak to them, I wouldn't rule anything out.
Meanwhile, McFadden has targeted a return to Scotland duty for the start of the World Cup qualifiers – once he finds himself a club.
McFadden added: "I haven't spoken to him (Levein) since the Liechtenstein game. The manager makes the decisions, does things his way and I have to abide by that.
"But I am still young enough and if I can get back playing to the level I am capable of, then the next thing is to try to get back into the Scotland team."