Rangers manager Walter Smith has demanded his team return to the consistent form they displayed in the first half of the season.
Rangers suffered their second Old Firm defeat this year in emphatic fashion as a Gary Hooper double and a Kris Commons strike earned Celtic a 3-0 win at Parkhead on Sunday.
Smith said: "The pressure is on us now to maintain the consistency we had in the first half of the season. I don't think we have been as bright since January, so therefore we have to look to get that back and continue to get wins."
He added: "And then once it comes to the last Old Firm game of the season, which is at Ibrox, we would hope we would have a bit of an advantage if we won that one."
Rangers will have to rediscover their form without a player who was instrumental in their impressive form before New Year after Steven Naismith went off at half-time at Parkhead with the recurrence of a hamstring problem.
Rangers revealed the problem stemmed from a car crash Naismith was involved in as he drove to training from Ayrshire on Christmas Day.
Smith said: "It's been a difficult one to treat and diagnose. He starts to feel better and then it flares up when he plays."
Naismith is almost certain to stay at home when Rangers travel to Portugal to face Sporting Lisbon in the second leg of the Europa League on Thursday following the 1-1 draw at Ibrox last week.
"It's more than likely he will miss the trip," Smith said. "I would think that he'll have to take a fair period of time before he can come back, just to make sure the injury does finally disappear."