Rangers took another huge step towards their first Scottish league title in a decade after Steven Gerrard's team claimed a 1-0 win over 10-man Celtic at Ibrox.
A tale of two McGregors came together to extend the Light Blues' lead at the top of the Premiership to 19 points - and place Neil Lennon's future as Celtic boss in fresh doubt.
It might have been a different story had Gers keeper Allan McGregor not pulled off three world-class saves - including brilliant finger-tipping Leigh Griffiths' strike onto the post.
But with Celtic unable to capitalise on a dominant first half, they left themselves vulnerable to a sucker punch and so it proved as Callum McGregor put the ball into his own net just seven minutes after Nir Bitton had been sent off.
Lennon's team still have three games in hand and two Old Firm games in which to claw themselves back into the title race but it looks increasingly likely this will be Rangers' year.
Ryan Kent was recalled by Gerrard despite his recent dip in form while Leon Balogun's started ahead of Filip Helander at centre-back.
Lennon opted for Bitton ahead of Republic of Ireland defender Shane Duffy to replace the injured Christopher Jullien. Vasilis Barkas was back in goal as he looked to make amends for his part in Celtic's defeat to Gers back in October.
However, skipper Scott Brown was again left out as Ismaila Soro was trusted to start his first derby.
The Parkhead men fired the first warning shot inside three minutes when Callum McGregor strode past James Tavernier before sliding in Edouard.
However, Allan McGregor made the first of his vital interventions as he palmed away before Tavernier blocked the Hoops' McGregor on the rebound.
There was a brief angry exchange between Lennon and the Rangers bench after Alfredo Morelos planted his studs onto Jeremie Frimpong's foot.
But the Northern Irishman had every reason to be pleased with how things were going.
Balogun looked nervy as he headed the ball straight to Turnbull. Griffiths was then teed up but McGregor again came to Rangers' rescue.
Gers were expected to dominate their rivals' narrow midfield down the flanks but instead Celtic's full-backs were the more prominent as Tavernier and Borna Barisic found themselves pinned down by the hungry Hoops' high press.
Rangers finally worked some territory on 20 minutes as Joe Aribo slung a low ball in for Morelos but Frimpong made an important block.
Leigh Griffiths then got away with a barge on Kemar Roofe in the box. Seconds later it was Gers breathing another sigh of relief as McGregor got his fingertips to the ball to brilliantly tip Griffiths strike' against the post.
Rangers were increasingly forced to go long by the squeeze from Celtic, with Kristoffer Ajer mostly eating everything up. Even when Roofe did get across the big Norwegian to flick on just before half-time, Diego Laxalt matched Morelos for pace before putting in a vital challenge.
Bitton flicked a David Turnbull corner wide with the last chance of the half as Rangers were relieved to get in at the break still on level terms.
Gerrard was forced into a change at the break as Roofe was replaced by Ianis Hagi and the Romanian soon flashed a shot across Barkas' goal.
But Rangers got a massive helping hand on 63 minutes when Bitton got his marching orders after tugging back Morelos as the Colombian looked set to dart onto a Tavernier pass in behind.
Lennon took off Griffiths as he shored up his backline by introducing Duffy but Gers sensed blood.
Barisic's shot was deflected wide and from Tavernier's corner, Aribo cut across McGregor's eyeline and the stand-in Hoops skipper could not react in time to stop the ball hitting his shoulder and flying past Barkas.
Celtic substitute Mohamed Elyounoussi pulled the trigger in search of an equaliser but his strike ended on top of Allan McGregor's net.
Duffy went in the book for cynical lunge on Hagi, as did Morelos and Callum McGregor during the following melee.
The final whistle brought a firework display from jubilant Gers fans outside the ground - and an angry snarl from Lennon as he came head to head with Gers coach Tom Culshaw before being dragged down the tunnel.