When the Inter and Milan starting XIs lined up before a cacophonous San Siro on Sunday, there were all the usual sights.

Fierce, steely stares, necks being flexed, legs shaken out. Big-match anxiety writ large.

Then there was Zlatan Ibrahimovic, turning around wide-eyed to survey the scene and wearing a big grin.

Perhaps he knew all along. Or thought he did.

Ibrahimovic's return to this fixture was a blessing for Milan, largely because it diverted the attention away from the gulf that has opened up between themselves and their great rivals since Antonio Conte took charge of the Nerazzurri.

"He is a champion who gives Milan quality and charisma," Conte said of Ibrahimovic in the build-up, although even in acknowledging this he could scarcely have envisaged the first-half evisceration his title-aspirants would endure, before turning the tables to top the table with a 4-2 derby win for the ages.

Now 38, Ibrahimovic's frequent aggrandisement – which always seemed to pinball between self-deprecation and a yawing lack of self-awareness – has come to grate as much as it entertains.

It was easy to conclude a Milan marooned in mismanagement and mediocrity had bought into the myth rather than the aging man the wrong side of major knee surgery when they offered him a route back from his expected retirement home in Major League Soccer.

The Rossoneri entered Sunday's game seven places and 19 points shy of Inter, but yet to taste defeat in the seven matches since Ibrahimovic's second debut.

In this Derby della Madonnina – a fixture where he, of course, knows both sides of the divide – he was Milan's talisman.

Stefano Pioli's team drove forward from kick-off and there were 67 seconds on the clock when Ibrahimovic lashed over on the volley from Samu Castillejo's cross.

The most striking element of the veteran's early contribution was his capacity to elevate those around him. Castillejo always had someone to hit from the right flank and was a constant threat, while Ante Rebic looked more like the player from Croatia's run to the 2018 World Cup final as opposed to the beleaguered individual Milan were recently hoping to send packing back to Eintracht Frankfurt.

The twinkle-toed Hakan Calhanoglu was the pick of the bunch, rifling against the post after nine minutes and popping up with palpable menace across the final third thereafter, never far away from a shrewd pass or lay-off to Ibrahimovic.

Inter were struggling to get out of their own half and, in line with trepidation painted across a touchline-prowling Conte, they fell behind.

Of course Ibrahimovic was involved, muscling above Diego Godin to knock down Castillejo's cross for Rebic to scramble past a bizarrely hesitant Samir Handanovic.

A VAR review did not spare Godin, the sort of reprieve it is hard to imagine would sit well with the gloriously grizzled centre-back. In mano-e-mano combat he simply came off second best to an opponent on a mission.

If Ibrahimovic's role in the opener was about brute strength, for number two he resorted to stealth, stealing into space at the far post as Milan Skriniar's gaze was diverted to the ball. Soon enough it was behind him and being nodded into the net by the man of the moment. Arms aloft, script fulfilled.

Only Conte and his warriors in blue and black, with the blood of an undulating Scudetto race in their nostrils, had other ideas.

Antonio Candreva thumped goalwards in the 51st minute. Blocked. Marcelo Brozovic thumped harder. 2-1.

In a flash, it was all square as a darting Alexis Sanchez was played onside by Andrea Conti's heal and he cut back for Matias Vecino to score.

Godin supplied the pass to Sanchez and the sense of Inter's centre-backs being freed from their earlier Ibrahimovic ordeal was underlined by Stefan de Vrij heading home, putting them on course for the sweetest of victories.

Ibrahimovic thundered a long-range free-kick just wide, crashing it into the advertising hoardings with the same force Milan's earlier dreams met reality, and a towering header hit the post.

Having just about negotiated the man with the occasional God complex, Conte brought on Victor Moses to set up a fourth for the prolific Romelu Lukaku. It's 54 points apiece with Juventus at the summit and Inter, with goal difference in their favour, might just have taken a significant step towards their promised land.