The Saracens rugby director had seen his side secure a hard-earned 28-19 away win over London Irish but McCall believes much hard work still remains.
Saracens face two must-win fixtures - away to Newcastle and at home to Exeter - after dropping from second to third in the table as Leicester leapfrogged them with their four-try bonus-point win at Northampton in the early kick-off.
McCall said: "Newcastle are fighting for survival so it's going to be tough. They won at Gloucester today and Gary Gold seems to have turned things around.
"They are two tough games to finish on but ones we will look forward to.
"We went 14-6 down today and you can go two ways. You can feel sorry for yourselves. The last 10 minutes of the first half were vital and we scored six points and clawed back the lead they had.
"Our second-half performance was outstanding. Our pack got on top and controlled the game."
Charlie Hodgson, restored to goalkicking duties in place of injured England marksman Owen Farrell, landed 23 points.
Hodgson kicked five penalties from five attempts, converted the only Saracens try, scored by flanker Will Fraser, and landed two drop goals.
McCall said: "They were giving a lot of penalties away and Charlie did what Charlie does best.
"He had a great game and our young fellows really stepped up. Will Fraser and Jackson Wray in the back row were magnificent, along with George Kruis in the second row and hooker Jamie George when he came on."
Sarries bounced back from their Premiership defeat by Harlequins and the Heineken Cup knockout at the hands of French side Clermont Auvergne.
McCall said: "It was a very important day for us after a couple of difficult weeks and we showed a lot of mental strength."
Victory came at the end of a week which saw coach Andy Farrell turn down England to pledge his future to Saracens.
McCall added: "It's a huge thing for us. Andy's a big part of what we want to do.
"The decision he's made indicates that the club's going places and there's a lot more to achieve.
"He said we've only scratched the surface and the project has only just begun. We've built the foundations and we need to build how we are going to kick on."
Irish suffered their seventh successive defeat but they did not fall behind until nearly midway through the second half.
Recently appointed director of rugby Brian Smith, who watched Hodgson deny them even a losing bonus point with his second drop goal in the last minute, said: "Sport can be pretty cruel.
"Charlie dropping that goal at the end and us coming away with nothing is a bit of a knife through the heart.
"But if you look at the positives, they are champions of the Premiership and 75 minutes into the contest we got ourselves into a situation where we could win the game.
"But that's probably been the story of our season. We were a little bit unlucky but they are a good side.
"They are clinical and they have a fair bit of class in that squad."
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