Battered almost into submission by a rampant but profligate Aberdeen side, it looked as if the Light Blues were heading for their fourth league defeat of the season after trailing for the majority of the match to Zander Diamond’s second minute goal.
The Dons proceeded to dominate but without adding to their tally and they were made to pay for their slackness in front of goal when de Boer headed Rangers level with just two minutes remaining of regulation time.
The goal was probably more than the Ibrox side deserved after an ineffective performance that started badly and got worse as the match progressed.
For a team that had garnered six cleans sheets from their previous seven outings, Rangers’ defence had looked distinctly uncomfortable as Aberdeen probed at them purposely from kick-off and within 76 seconds they were behind.
It was a clumsy goal to concede, with Michael Ball and Craig Moore colliding as they sought to clear Scott Morrison’s free-kick leaving Diamond free to bundle the ball past Stefan Klos from a matter of yards.
For Alex McLeish this start was about as welcome as Johnny Beattie in the front row of a funeral and it could have been worse as Aberdeen went on to dominate their Glasgow guests.
As has often been the case over the past five years, it was left to Klos to prevent further damage and he turned Paul Sheerin’s drive around the post before performing further acrobatics to tip Russell Anderson’s header over the bar from the resulting corner.
Rangers offered little in response, with Ronald de Boer and Shota Arveladze often left isolated up front as Aberdeen bossed the midfield areas.
McLeish had seen enough by this stage and – after Leigh Hinds had battered the top of the crossbar with a long-range effort – the unfortunate Christian Nerlinger was hooked off after just 26 minutes, with Hamed Namouchi sent on in his place.
The change, however, did little to disrupt the flow of play towards Klos’ goal and only another brave stop from the German denied Markus Heikkinen after the Finn had robbed Nuno Capucho wide on the right touchline.
Lucky to be just a goal down at the break, McLeish tinkered with his side again bringing on Paolo Vanoli for Michael Ball at half-time in a bid to claw back the deficit and Arveladze had a chance to draw his side level after 56 minutes but blazed his attempt wide.
The Light Blues were starting to creep back into proceedings although they were often wasteful with the final ball after working their way into good forward positions.
In one frustrating cameo, Capucho dribbled encouragingly into the box but instead of crossing chose to turn back into his marker three times in succession and the moment was lost.
He had a chance to make instant amends when he cottoned onto Mo Ross’ right-wing centre but could only drag his shot wide of goal and watched on moments later as David Preece comfortably plucked his tame header out of the air.
Aberdeen rallied from that let-off. Substitute Bryan Prunty firing wide moments after coming on after being set free by Chris Clark before Klos parried Kevin McNaughton’s cross with Arveladze scrambling to hack the loose ball away from the danger area.
The Dons were edging closer to a second goal and Klos pulled off another great block from Leigh Hinds before ex-Celtic man Prunty watched another of his shots sail over the crossbar.
You began to wonder if Aberdeen may just pay for their profligacy and with just two minutes remaining Rangers surprisingly drew level.
Ricksen was fouled wide on the right and when Vanoli swept over the free kick Frank de Boer was first to react to nod the ball past the helpless Preece.
ABERDEEN (4-3-3): 1 Preece; 17 McNaughton, 27 Diamond, 5 Anderson, 24 Morrison; 29 Hekkinen, 10 Sheerin, 14 Clark (Muirhead 79); 19 Zdrilic, 9 Booth (Prunty 72), 7 Hinds
Subs not used: Esson, McGuire, Foster
RANGERS (4-3-3): 1 Klos; 21 Ross, 5 F de Boer, 3 Moore, 18 Ball (Vanoli 46); 2 Ricksen, 4 Emerson, 8 Nerlinger (Namouchi 26); 20 Capucho, 14 R de Boer (Mols 76), 7 Arveladze
Subs not used: McGregor, Hutton
Booked: Emerson (74)
Man of the Match: Stefan Klos