A 2-0 first-leg victory at the Emirates put Newcastle within touching distance of a second final appearance in three seasons, and with just four minutes on the clock, Eddie Howe’s side looked to be one step closer to that ambition.
Breaking swiftly from Arsenal’s goal-kick, the hosts worked the ball to Alexander Isak, who lashed an effort high into the net with clinical precision.
However, after a VAR check, referee Simon Hooper announced the offside decision to a disgruntled St James’ Park.
Soon after, neat play from the Gunners almost halved the aggregate deficit when Martin Odegaard sliced a spinning ball onto the post - a miss that was quickly punished by the home side.
Unfazed by his disallowed goal, Isak latched onto a goal-kick from Martin Dubravka, playing a one-two with Anthony Gordon before racing through and striking the post, which left David Raya wrong-footed and unable to prevent Jacob Murphy’s cushioned follow-up.
The visitors now had a mountain to climb, and with Leandro Trossard being denied by a low reflex save before half-time, the Gunners only had 45 minutes to save their League Cup campaign.
Having demolished Manchester City 5-1 on Sunday, Arsenal were looking far from comfortable against a confident Newcastle side, and given that just one of the previous 14 head-to-heads had seen both teams score, the omens weren’t positive for a second-half turnaround.
The interval didn’t have the desired effect for a nervous Gunners backline, who were twice exploited in the early stages of the second half.
A loose touch from William Saliba wasn’t punished when Gordon’s long-range snapshot bounced wide, but Raya wasn’t so fortunate, seeing his pass cut out by Fabian Schar, allowing Gordon to slot home on the turn.
Content with a healthy aggregate advantage, Newcastle eased through a rather uneventful second period to secure their spot in the final.
They will find out their opponents tomorrow when Liverpool host Tottenham Hotspur, with Spurs 1-0 up from the first leg and potentially standing between the Magpies and their first-ever League Cup triumph.
Meanwhile, a first defeat in nine away games across all competitions means Arsenal’s search for a first EFL Cup final since 2017/18 goes on, having last lifted the trophy in the 1992/93 campaign.