Eddie Howe’s side, who were EFL Cup runners-up in 2023, survived an early wave of pressure before Isak put them in front late in the first half of Tuesday’s semi-final first leg, then Gordon’s close-range finish gave them breathing space shortly after the interval.

They now have a two-goal cushion to defend when the sides reconvene for the second leg at St James’ Park on 5 February, when Mikel Arteta’s Gunners will require a big improvement.

Jurrien Timber headed over when left unmarked in a good position early on, which set the tone for Arsenal to dominate long periods of the first half without making the breakthrough.

Their best opportunity of the period came just before the half-hour mark, as Gabriel Martinelli broke clean through on goal. The Brazilian beat Martin Dubravka with his near-post effort, only to see the ball bounce off the upright.

Their wastefulness was punished in the 38th minute as a deep Newcastle free-kick somehow found Jacob Murphy. His touch fell at the feet of Isak, who crashed his finish off the underside of the crossbar and in.

Things got worse for Arsenal six minutes into the second half as David Raya could only parry Isak’s shot into the path of Gordon, who tapped into an empty net to make it 2-0.

Kai Havertz fluffed his lines from six yards out and Jorginho fired over the crossbar as Arsenal went in search of a lifeline, but they were unable to cut the deficit and now need a memorable comeback on Tyneside next month.

City defender Josko Gvardiol had put the visitors ahead after 35 minutes when he finished smartly from Jack Grealish’s lay-off.

However, while Mateo Kovacic and Rico Lewis combined well in covering for the influential Rodri, who has been ruled out for the rest of the season with a knee injury, City eventually buckled during Newcastle’s best spell of the game just after the break.

When Bruno Guimaraes played an excellent pass through the City defence, Kyle Walker played Gordon onside and the England forward went down under Ederson’s challenge. Ederson was booked and Gordon kept his cool to send the Brazilian the wrong way from the spot.

Pep Guardiola’s side should have been further ahead at the break but Ilkay Gundogan fluffed his attempted chip after Newcastle keeper Nick Pope had presented a clearance straight to City when he was a long way out of his goal.

Both sides tried to force a winner, with Newcastle substitute Sean Longstaff going close for the hosts and Bernardo Silva testing Nick Pope deep in stoppage time.

The Magpies remain with only one win in 34 top-flight meetings with City, who have now dropped four points in the space of a week after their 100% start to the campaign.

But the victory came at a price as goalkeeper Nick Pope suffered what appeared to be a serious shoulder injury.

In-form Gordon tapped in Kieran Trippier’s low cross at the far post to give Newcastle a richly deserved success that took them above their opponents and to within reach of the Premier League’s top four.

It came 31 days after Eddie Howe’s side recorded an emphatic 3-0 victory at OId Trafford in the Carabao Cup.

Howe’s already injury-ravaged side should have been in front before the break as Alexander Isak’s shot was deflected narrowly wide by Harry Maguire before Trippier’s brilliantly struck free-kick bounced to safety off the underside of the bar.

When a goal finally came for Newcastle, there was no surprise it should come from Gordon, whose left-sided partnership with Tino Livramento had been too much for Manchester United to cope with.

Newcastle’s win means they have beaten Manchester United in three consecutive games for the first time in more than a century.

Aaron Wan-Bissaka denied Newcastle a second with an inspired goalline block, only for Fabian Schar to do something similar to keep out Sergio Reguilon’s effort, the nearest the visitors came to avoiding their sixth defeat of the campaign.

However, it was in trying to save that Pope was hurt, with the Englishman immediately signalling he could not continue.