Motherwell remain in third place, but are now looking over their shoulders, with Dundee United now having closed the gap between the two sides to just five points.
And McCall knows it is vital he gets a reaction from his side when they visit Hibs on Sunday.
Indeed, with Peter Houston's side scheduled to face Aberdeen at Pittodrie 24 hours before Well's trip to Easter Road, the gap could be down to just two points when the Lanarkshire men run out in Leith at 12.30pm.
But the Fir Park gaffer remains bullish about his side's ability to retain third place and the Champions League third round qualifier slot on offer for next season.
McCall said: "We definitely deserved at least a draw against Rangers, but what we can't afford to do is to obsess about the result.
"We must take the positives from the performance on to Sunday's trip to Hibs and make sure that we perform to the same level as we did against Rangers.
"The target when we started the season was to make the top six. By Christmas that had moved on to try and get in the top four and now, as it has been for the last month or so, it is about finishing third.
"Obviously it is disappointing to lose to both Kilmarnock and Rangers in succession and it is vital we do not let the negative momentum, in terms of results, grow.
"But I couldn't have asked for any more from the boys in terms of effort and the quality of play we got from them against Rangers. It has to be more of the same at Easter Road this Sunday."
Motherwell's hopes of bouncing back from their third defeat at the hands of Rangers this term have not been helped by the suspensions of Stevie Hammell and Steve Jennings.
And McCall added: "Suspensions hit all sides at some stage and we seem to be at that stage right now.
"Jenno and Hammy are big players for us and to have them both out at the same time is a blow. But we have players who can come in and supply the versatility that will be needed to cover for their absences."
McCall will hope club captain Stephen Craigan will return from a hamstring injury, which would allow Tim Clancy to shuffle over to the left flank to cover for Hammell's absence.
And young midfielder Stuart Carswell, who deputised for Keith Lasley during his suspension, should cover for Jennings.
But long-term injury crock Stevie Saunders will not be rushed back into the team, despite playing in a bounce game as he recovers from cruciate ligament damage.