The frontman notched his first less than five minutes in, running onto a superb Siem de Jong ball before producing a confident finish.

Jamie Walker restored parity for the home side, just seconds after Esmaël Gonçalves had blazed a spot-kick over the crossbar.

They were not level for long though, as Gayle netted his second after meeting Jonjo Shelvey’s corner.

The game quietened down after the break, with United fielding a completely different XI by the close of play. But, on a rainy evening in the Scottish capital, they rarely looked like relinquishing their lead.

The Magpies were unfortunate not to break the deadlock after only 72 seconds. Rolando Aarons found a pocket of space just inside the area and, after checking inside, smashed the ball against the crossbar with his unfavoured right foot.

With their next attack, though, Rafa Benítez’s side opened the scoring. De Jong produced a smart turn just inside the hosts’ half and played an inch-perfect pass through to Gayle, who calmly rolled the ball beyond Jack Hamilton.

Newcastle continued to dominate, with Aarons, Mohamed Diamé and Christian Atsu all going close.

Out of nowhere, though, Ian Cathro’s troops were handed a lifeline, as Massadio Haïdara was penalised for a challenge on Walker deep inside the Magpies’ 18-yard area. Gonçalves stepped up, but sent the ball flying into row Z.

The Portuguese wide-man would have been relieved seconds later, then, as Walker levelled the scores after pouncing on a loose ball 12 yards out.

There was no sign of the goalmouth action letting up. Midway through the half, de Jong met a well-weighted Shelvey corner in a central position, but saw his header palmed clear by Hamilton.

The Jam Tarts did not heed the warning, however, and two minutes later, another Shelvey delivery dropped kindly for Gayle at the far post, and the frontman bundled the ball over the line.

Both ‘keepers withstood a scare just after the half-hour mark. First, an Aarons cross from the left almost dropped over the head of the hosts’ Hamilton, with the ball coming back off the woodwork. Then, at the other end, Rob Elliot could only watch as Gonçalves’ fizzing drive struck the base of the far post.

Having had little to do for much of the first half, Elliot was called into action twice before the break, producing a smart parry to deny the lively Walker, before getting back across his line quickly to push Gonçalves’ header wide.

New signing Florian Lejeune was among those to enter the fray for the Magpies for the second half, with attacking duo Aleksandar Mitrović and Ayoze Pérez also coming on.

And Pérez was involved immediately, just clearing the crossbar after Hearts failed to clear Henri Saivet’s corner from the left.

With 55 minutes on the clock, Hamilton almost fumbled a low Mitrović cross into his own net. Something of a panic followed in the hosts’ backline, but the ‘keeper recovered to mop up Saivet’s driven effort.

A replacement for Chancel Mbemba at right-back, Jesús Gámez looked lively going forward after taking to the pitch. Just after the hour-mark, he picked out Mitrović’s run through the middle, and the Serbian planted a header over the top.

A quiet period followed, with the game becoming increasingly fragmented. With less than a quarter of an hour remaining, Hamilton looked to punch clear an in-swinging Pérez free-kick, but the ball ricocheted against teammate Jamie Brandon before trickling narrowly wide of the post.

With the last action of the evening, Lejuene almost ended his debut in perfect fashion, nodding an Achraf Lazaar corner just wide of the near post.