Resurgent Celtic came from two goals down to salvage a dramatic point in the 91st minute against Rangers to leave Scottish Premiership leaders Hearts with a commanding lead over both Old Firm sides.
A sensational early double from Rangers striker Youssef Chermiti was kick-started by a world-class opener - a wonderful overhead kick reminiscent of Scott McTominay's for Scotland against Denmark late last year.
After claiming a double at Celtic Park at the turn of the year, the Portuguese forward repeated the feat on home soil as a rejigged Celtic defence completely wilted under the pressure.
Dane Murray's botched clearance allowed Chermiti to pounce once again, with the former Everton man slipping past first Julian Araujo then a stunned goalkeeper Viljami Sinisalo, deputising for the ill Kasper Schmeichel.
It was a blow from which Celtic looked unlikely to recover at the break, but manager Martin O'Neill changed the dynamic by throwing on Reo Hatate and Sebastian Tounekti at half-time.
Both were involved in the goal which gave Celtic hope, a move finished when Kieran Tierney headed powerfully in from Benjamin Nygren's cross.
Celtic dominated the second period with Jack Butland denying Daizen Maeda and Luke McCowan, but late drama was to come.
Maeda was denied by an incredible Butland save from point-blank range, but after a video assistant referee review, Dujon Sterling was punished for a handball before his keeper's intervention.
Hatate's penalty and rebound were both saved brilliantly by the Rangers keeper, but the Japanese midfielder bundled the ball in with just a couple of minutes to go - changing not just the scoreline but the complexion of the title race.
The main beneficiaries may well be Hearts whose lead at the top is now six points. Rangers stay second but will be overtaken by their city rivals if Celtic can win their game in hand in midweek at Aberdeen.
This result keeps things nicely at boiling point at the top of the table and increases the likelihood of a four-way tussle for the title, with Motherwell just a couple of points off third-placed Celtic.