After being knocked out of the Scottish Communities League Cup by Rangers, Well were then knocked off the summit of the SPL by a rampant Celtic, also losing their unbeaten start to the current league campaign.
But with Dundee United next up at Fir Park on Saturday, McCall is remaining positive.
The Steelmen gaffer said: "What is vital for us is that we don't allow any doom or gloom to descend over us. We have Dundee United next up at Fir Park and it is vital that we bounce back with a home win.
"I have told the lads that the success or otherwise of our season will not be decided by how we do against Celtic but rather how we go against the likes of United, Aberdeen, Hibs and Hearts.
"So we need to show some character and self-belief and we need to provide a response and from my point of view it is a huge plus that we have the opportunity of a home game to do that.
"We are sitting just one point behind Celtic with a game to go until the end of the first quarter and if we can get the win over United then it will have been a more than decent start to the campaign."
With United having lost their last two games on the bounce and conceded seven goals in doing so, McCall's men are meeting the Tayside team at the best time.
But the Well boss has no doubt that his young side must learn lessons from the last week.
He said: "Sometimes you have just got to take your hat off and say that you were beaten by the better side.
"I thought Celtic's movement was outstanding and our young defenders have had a painful lesson to learn from the game.
"But the good news for them, as I said to them after the game, is that they will not need to worry about facing that level of quality week in, week out.
"So the Celtic game has gone now and as long as we lean the lessons from it and take it on the chin we will be fine."
McCall added: "We know United have not been on the best of runs recently but they have some fine players in their ranks who can hurt any side.
"So it will be up to us to make sure we produce our best on Saturday."