Celtic opened up a significant six-point gap over Rangers at the top of the cinch Premiership with a 2-1 comeback win at Ibrox.
Gers' on-loan midfielder Aaron Ramsey scored just three minutes into his first Old Firm game with a close-range finish, but Hoops midfielder Tom Rogic levelled four minutes later and defender Cameron Carter-Vickers had the 700 travelling fans in raptures when he fired the visitors ahead just before the interval with a goal that proved decisive.
With six fixtures remaining including another Old Firm game at Parkhead - as well as a Scottish Cup semi-final between the two Glasgow giants - Ange Postecoglou's side are on course to bring the title back across the city, helped by a goal-difference advantage of 16.
Giovanni van Bronckhorst's men face Braga in the first leg of their Europa League quarter-final tie in Portugal on Thursday - their boss Carlos Carvalhal was watching from the stands - but their domestic aspirations suffered a huge blow at the hands of their bitter rivals.
The home side had been struck by a significant injury blow in the build-up to the keenly-awaited encounter in Govan.
Colombia striker and Gers top scorer Alfredo Morelos was ruled out with a muscle issue and he was replaced by Kemar Roofe, while Ramsey replaced Glen Kamara.
Postecoglou had promised to go all out for the win but the Light Blues sprang out of the traps and Ramsey opened the scoring in the third minute when he knocked in a Ryan Kent cross after the wideman had been put through by defender Calvin Bassey.
The Govan side drove for number two and a couple of dangerous deliveries zipped across the Celtic goalmouth.
However, in the seventh minute after Gers keeper Allan McGregor had parried a 25-yard drive from Reo Hatate, fellow Parkhead midfielder Rogic - who had shrugged off a knock to play - returned the ball high into the net.
Celtic began to dominate and Rogic ended a swift move in the 25th minute by firing over from 16 yards.
In the 33rd minute Rangers midfielder Joe Aribo went tumbling in the penalty area under pressure from defender Carl Starfelt as he moved for a James Tavernier cross but referee Willie Collum ignored loud penalty claims.
At the other end, McGregor thwarted Daizen Maeda as the Japan attacker tried to round the keeper in the box and Rogic's follow-up shot from the loose ball struck Bassey, with the danger eventually cleared. Moments later Celtic attacker Giorgos Giakoumakis headed a Jota cross past the post.
McGregor raced out to block Maeda - this time Celtic appealed for a penalty - but a Hoops goal was on the cards and three minutes from the break, when Rangers failed to clear Jota's free-kick from wide on the left, Carter-Vickers spun and drilled a left-foot shot low into the net.
The start of the second half was delayed as groundstaff cleared glass from a broken bottle from the Celtic goalmouth but when play got under way, the Light Blues tried to reassert themselves.
There was another Rangers penalty claim when Ryan Jack's cross struck Carter-Vickers but again play went on.
Matt O'Riley and Nir Bitton replaced Rogic and Hatate in the Celtic midfield while Ramsey and Jack made way for Fashion Sakala and Scott Arfield as tempers began to fray.
Rangers enjoyed a spell of pressure and in the 75th minute Celtic keeper Joe Hart made a good save from a Sakala shot.
Moments later, Celtic substitute Liel Abada, on for Jota, passed up a great chance provided by Giakoumakis when he missed the target from 10 yards. McGregor then tipped another Abada effort over the bar.
Back came Rangers and Roofe turned a Connor Goldson cross over the bar but in the end Celtic held out for the win that might just prove to be critical.