Chelsea's style has shifted, the muscular grind of the recent past replaced with flamboyance and flair, but the stubborn refusal to wilt in this competition remains. As this thrilling contest tore relentlessly into added time their grip on the trophy felt loosened, the prospect very real of becoming the first holders to see their defence stumble at the group stage, after two bruising collisions with Shakhtar Donetsk and with Juventus having finally stirred. Yet, by the final whistle, they were a side revived.

The decisive intervention on an evening illuminated by the brilliance of Brazilians on both sides and a goal from a Spanish golden boot winner was provided by a talent nurtured across the Thames in south London. Victor Moses had entered the fray for Oscar nine minutes from time, the youngster developed at Crystal Palace and prised from Wigan initially gasping to adjust to the frenzied pace of the game as Chelsea strived desperately for a winner. They might have been prised apart themselves in stoppage time but, amid the anxiety, somehow claimed a 93rd-minute corner, swung over by Juan Mata, and Moses, albeit at a relatively slight 5ft 10in, mystifyingly went ignored by Shakhtar's disjointed defence.

The winger's spring into space between defenders was timely, his header firm beyond the hapless Andriy Pyatov and, from playing catch-up, the holders – staggeringly – had wrested back some authority in the group.

Avoid defeat in Italy in a fortnight and a victory over the section's whipping boys, Nordsjaelland, will propel them into the knockout phase. "It was crucial for us, but the group will still probably go down to the last game, and maybe even the last kick of that last game," warned Roberto Di Matteo, though Moses has ensured his side's destiny remains in their own hands.

There was disbelief in defeat for Shakhtar. Their manager, Mircea Lucescu, spoke of "disgust" at the flashes of defensive ill-discipline that provided all three of the hosts' goals, complaining that it was "impossible for a team to have played this well and lost". Certainly, few sides have visited Stamford Bridge and shredded the hosts so impressively in recent years, the visitors' rat-a-tat attacking exchanges mustered at breathtaking pace. Fernandinho's dart to the byline, away from Ramires and Ryan Bertrand, and astute pull-back to be dispatched by Willian for Shakhtar's first equaliser had set the tone.

The speed at which Alex Teixeira, Fernandinho and Luiz Adriano subsequently combined, with the first skimming a shot beyond Petr Cech's far post, was jaw-dropping. Chelsea were still finding their feet in the second half when Willian, Fernandinho and the marauding Darijo Srna sliced through their hosts' left flank for Willian, courted by the Londoners in January, to register again. That was the 14th goal they have conceded in six games, placing under greater scrutiny the decision to omit a rusty John Terry – apparently blunted by his four-game domestic ban – despite the enforced absence of Ashley Cole.

Di Matteo admitted it had been "difficult" to inform his captain he would not be starting, and conceded some semblance of defensive solidity must be restored in Turin. "Certainly we have to work on the organisation in general," said the manager. "There were two players slipping at the first goal, and at the second goal we had plenty of players in defence to deal with the cut-back. We weren't outnumbered." They were always vulnerable, even if this is a team capable of fighting fire with fire.

The visitors may have been illuminated by a gaggle of Brazilians but the hosts had their own to savour and their opponents' similar defensive fragility to exploit. Pyatov endured a dismal evening, his early panicked attempt to clear from Yaroslav Rakitskiy's unhelpful backpass having been deflected into the net by Fernando Torres's lunge. That was the Spaniard's 100th goal in English football and further reward following the award of the golden boot for Euro 2012 in the buildup to the game. In contrast, Pyatov's misery had only just begun.

The Ukrainian might have been content with his decisive header to clear Mata's optimistic cross five minutes from the interval as the ball flew to Oscar, a distant figure emerging from the centre circle. Yet the youngster spied the goalkeeper out of his box, with his opportunistic riposte soaring gloriously into the gaping net from 40 yards. It was an astonishing finish but one in keeping with the helter-skelter nature of a contest that, by the end, had thrust Chelsea closer to the knockout round. Di Matteo is working with a new Chelsea team, but the old indomitable spirit remains.