It was around six seconds from time here, with the fourth official preparing to hoist his board on the touchline, when ­Fernando Torres buried Manchester City's prospects and, in the process, confirmed his personal renaissance. Pinball in midfield had culminated in Willian's punt over a backtracking Matija Nastasic, the centre-half panicking as he stretched to nod back to Joe Hart.

The Serb might just have caught sight of his goalkeeper's close proximity as he made contact on the edge of the area, then watched the ball loop over his team-mate whose sprint, mystifyingly, ended up carrying him well outside his penalty area. There was Torres, tearing beyond the visitors' confused last line of defence and away from a leggy Martin Demichelis, to convert into the gaping net.

City players crumpled to the floor, Nastasic burying his face in the turf while Hart retrieved the ball from the net and could be seen screaming "keeper's, fucking keeper's" in livid frustration. The pair were culpable but the Englishman had put himself in no position to collect, intercept or divert. He wore the look of a guilty man.

Torres's name was chanted all around, the chorus persisting as José Mourinho extricated himself from the crowd behind the visitors' dug-out where he had apparently dived – much to Manuel Pellegrini's disgust – to celebrate with his son, José Jr. This was the second week running the Portuguese has ended up in the crowd ­following last week's dismissal against Cardiff City, but this time he was not the centre of attention. That was reserved for Torres alone.

This performance summed up the Spaniard's Chelsea career, veering as it did from the ridiculous to the sublime, though it was the manner in which he recovered from the former to serve up the latter that suggested that his inner strength has been restored. The 29-year-old had been guilty of a dreadful miss on the half-hour, spooning over Ramires's fine pass when free and alone near the penalty spot. In the recent past a miss so glaring might have left him cowed, his display shrivelling thereafter. Here it served to galvanise.

Within minutes he had embarrassed Gaël Clichy with his pace across the grass, the full-back left gasping in his vapour trail, before squaring for André Schürrle to tap in a first Chelsea goal. Then there was the shot curled sumptuously on to the angle of post and bar as half-time approached that left Mourinho slumped over the wall in his dug-out, aghast that one of his players could be so bereft of fortune. This, after all, was a striker who had scored only once in the league – on last season's final day – since December. Those manic celebrations at the end greeted the breaking of a drought.

"It was a fantastic performance and, even better, because it came after an easy goal was missed," said Mourinho. "When a striker misses an easy chance, he can be affected for the rest of the game. But it was like that was the moment he decided he would be man of the match. The fans were amazing and supported him, saw how hard he worked for the team and saw his heart."

Torres has been prolific in Europe this year, albeit largely in the Europa League, but it should be noted that his best ­performances under Mourinho have now come against sides of better quality: Bayern Munich in the Uefa SuperCup, ­Tottenham Hotspur in the league, Schalke in the Champions League in midweek and now City.

The trend has been upwards, certainly since half-time at White Hart Lane last month, even if that particular afternoon had ended with his dismissal and that unpunished but catty scratch at Jan ­Vertonghen. Rafael Benítez could not coax displays this menacing from his ­compatriot during last season's interim spell in charge. "It would be easy for me to say that we did this or that but we did nothing," added Mourinho. "We believe our ­methodology improves players' sharpness and speed in the first 15-20 metres. We work high intensity for short periods and that helps them to become sharp. But he's responsible. I don't know if he was the same last year but since I arrived he's worked very, very hard every day."

This was his and Chelsea's reward, the dramatic nature of the victory ensuring City departed bruised as well as beaten. They must have thought they had wrested control of this contest having started the second half with such urgency, the excellent Sergio Agüero – "a powerful tank," according to Mourinho – darting behind Gary Cahill to collect Samir Nasri's pass and thump a glorious finish high beyond Petr Cech at his near post. City had never previously lost a Premier League game when their thrilling Argentinian had scored and, had David Silva not been guilty of over-elaborating and Javi García mustered a more convincing header from the Spaniard's free-kick delivery, that record might have been maintained.

As it was, they had seemed content enough with a point, particularly given recent failings at Cardiff and Aston Villa, only for Hart's rush of blood and Nastasic's header to provide a sting in the tail. The lack of communication between goalkeeper and centre-half was damning, the scrutiny fixing inevitably back on the England keeper whose untouchable status for club and country now looks fragile. ­Pellegrini, riled by Mourinho's dash across his box, hardly offered a vote of confidence in his later mumbled assessment. It all seemed as damaging to City as it was rejuvenating for Torres.

Man of the match Fernando Torres (Chelsea)