VICTOR Moses came off the bench to head home a Juan Mata corner in the fourth minute of injury time and transform Chelsea's Champions League campaign at a stroke.
With the Blues struggling against a supremely gifted Shakhtar side, it was beginning to look as if qualification for the knock-out stages might require victory in Turin against Juventus.
As it is, a draw in Italy will leave them well placed to finish the job in the final match against Nordsjaelland at the Bridge. Such are the narrow margins in this year's fraught adventure.
It has to be said that the win was a travesty, with the visitors arguably meriting all three points, let alone a draw.
They produced one of the most polished displays seen by a visiting team in recent seasons and but for some catastrophic errors by their goalkeeper, they would have gone home leading the group by more than just away goals and locked on seven points with Roberto Di Matteo's men.
As it is though, Moses – who came on for Oscar with 10 minutes left - must now feel he has laid down a big marker at his new club.
In a game that never let up, Chelsea needed the generosity Andriy Pyatov to stay ahead of the game – and they were fortunate to go in 2-1 ahead at the break.
The hapless stopper paid the price for a lax pass out to a defender and was rushed when he found it coming back his way and Fernando Torres bearing down on him.
Torres stuck out a leg and Pyatov's attempted clearance bounced off the Spaniard and into the net with the game only three minutes old.
If that goal looked likely to herald a comfortable home win, the Ukranians soon disabused the European champions of the notion with their relentless ambition and attacking intent.
Not for them the blanket defence favoured by most opponents who have ventured to the Bridge for group stage matches down the years.
The orange shirts swarmed forward with pace and imagination – their movement often catching Chelsea cold.
It was a wonder that their only reward was a goal from Willian three minutes later – the striker tucking home after Fernandinho had ghosted past Ryan Bertrand – who slipped when turning – and pulled the ball back from the byline.
More chances followed for the confident visitors, and yet it was the Blues who got their noses in front on 40 minutes when Pyatov rushed out to head clear a ball from the left by Mata.
Unfortunately for the Ukranian international, the ball landed in Oscar's orbit and after taking a touch to control it, the Brazilian lobbed the ball 35 yards over the stranded keeper.
Some kind of justice was done for all Shakhtar's fine play two minutes after the restart, when Willian grabbed his second goal of the night – pouncing after skipper Darijo Srna had raced on to a defence splitting pass to pull another undefendable ball back from the byline.
Chelsea - who surprised by leaving John terry on the bench - were relieved that the equaliser did not quite inspire Donetsk to even greater deeds, although Petr Cech was relived to see Razvan Rat's effort ping back off a post, while some menacing counter-attacks kept home fans anxious to the bitter end.
The Blues, in truth, would have been grateful for a point. But the late twist gave them more than even they had bargained for.
Line-up: Cech; Ivanovic, Cahill, Luiz, Bertrand; Ramires, Mikel; Mata, Oscar (Moses 81), Hazard; Torres (Sturridge 90). Subs not used: Turnbull, Terry, Romeu, Marin, Azpilecueta.
Attendance: 41, 607