Advocaat's side now hold only a six-point advantage over Celtic after they lost 3-1 at St Johnstone on Sunday night. All they had to show for dominating most of the match was a second-half header from Craig Moore against a side they hammered seven past on their last visit to Perth.
Poor marking led to Saints' captain, Jim Weir, opening the score in the 13th minute. After Moore, back from his spell at Crystal Palace, had equalised more slack defensive work allowed the substitute Miguel Simao to seize on Nick Dasovic's knock-back to put the home side back in front.
Kieran McAnespie's injury-time third rubbed salt into the Rangers wounds and, although Advocaat still believes his side will take the title in May, his players need to heed a few harsh words.
The Dutchman complained that Saints had created only four chances but had scored three times. "Everyone knew who they were supposed to take at the free-kick which led to their first goal and the second was even worse," he said. "Sometimes I have a feeling that my defenders want to do things in a nice way that looks good. I'm not interested in what looks nice, I want the ball away from the goal. Our defensive work was very poor and that shouldn't happen at this level."
Rangers have lost twice on the trot and Advocaat must now raise his players to take on St Johnstone again, in the Scottish Cup semi-final at Celtic Park on Sunday.
They will need to find a cutting edge. Only Rod Wallace and Jorg Albertz came close to matching their exalted reputations and their wide men, Neil McCann and Andrei Kanchelskis, endured miserable evenings.
Advocaat was also upset by newspaper reports linking Rangers with Hakan Sukur, Galatasaray's pounds 13m-rated Turkish international striker.
"As for Sukur, I don't know where he lives or what he looks like," he said in dismissing the reports. "It is unfair to our fans to keep bringing these players up. You might as well say we are going to sign Ronaldo."
The St Johnstone manager, Sandy Clark, was delighted to have avenged that 7-0 humiliation. "It has kept being brought up but I have tried to tell people the circumstances that night were exceptional."
The entire Saints rearguard could take immense satisfaction from a near- perfect display. Despite Rangers' territorial dominance, there always seemed to be a body in the way to quell the danger. Their goalkeeper Alan Main was at fault in failing to collect the corner from which Moore scored from Tony Vidmar's knock-back, but otherwise he did his international claims no harm under the watchful eye of the Scotland coach, Craig Brown.
The victory kept Saints on course to finish the season in the top three, although they would accept they are not the equals of the two Glasgow clubs. "Rangers have some incredible players that frighten the life out of you," Clark said. "When you spend pounds 34m you get some of the best players in the world. We have really done well to beat them and I just want all my players to enjoy this victory."