Antonio Rüdiger’s eyes widened in alarm. It could not be happening again, could it? The Chelsea defender had already got in the way of a deflected Nacho Monreal header to concede an own-goal equaliser in this helter-skelter Carabao Cup semi-final, second leg.

It was happening again. Alexandre Lacazette had found a small pocket of space following a forward surge but Chelsea looked to have him under control. The Arsenal striker dug out a low cross and, almost in slow motion, it deflected off Rüdiger to fall perfectly for Granit Xhaka. The Arsenal midfielder stretched out a leg and, following one more thump of Rüdiger’s heart, the ball was on its way into the far corner for the winner.

Arsène Wenger works out Chelsea’s Hazard dependency to earn Wembley date | Barney Ronay Read more

It had been impossible to separate these rivals over 90 minutes in four previous meetings this season and it felt as though it might take something freakish to do so this time. Rüdiger provided it and so Arsenal will face Manchester City in the final next month. Arsène Wenger has never won this competition. Is the wait about to end?

It was the most eclectic of tactical triumphs for the Arsenal manager. He had lined up in a 4-3-3 formation but, after a wobbly start, he switched to a system with wing-backs and Mohamed Elneny in front of the three centre-halves.

Wenger’s more advanced midfielders interchanged positions, with Mesut Özil in a particularly free role. Jack Wilshere said that “we might have got the formation wrong in the first 25 minutes”.

Quick guide Arsenal player ratings Show Hide David Ospina Not much more to do than retrieve the ball from his net after Hazard’s goal. Almost incident-free. 6/10

Héctor Bellerin Still not in peak form, had a battle on his side with Alonso and made a crucial block late on. 6 Laurent Koscielny A reassuring presence in a defence as variable as Arsenal’s, led by strong example. 7 Shkodran Mustafi Slack passing and reckless concentration early on but recovered to be more robust with keen interceptions. 6 Nacho Monreal Penalty area predator du jour, elated to claim Arsenal’s equaliser which took a double ricochet. 7 Mohamed Elneny Arsenal improved when he dropped assuredly to reset into a more solid back three. 8 Granit Xhaka Determined and enterprising. Advanced into more offensive positions than usual and got his reward with a deserved goal. 8 Mesut Özil The ray of creative light, looking for spaces and openings. Not everyone on his cerebral wavelength. 8 Jack Wilshere Not his most eye-catching performance but wanted to influence midfield. Booked for catching Barkley. 7 Alex Iwobi Tried to be sensible, helping out at the back. Should have sealed it on the break but shot timidly and straight. 6 Alexandre Lacazette At times lost, at others offside, still made critical impression creating Xhaka’s matchwinning goal. 6 Subs Aaron Ramsey (replaced Iwobi 83, 6), Calum Chambers, Ainsley Maitland-Niles, Kolasinac (replaced Lacazette 83, 5), Matthew Ryan Macey, Reiss Nelson, Eddie Nketiah.

Wenger firmed up his changes at the interval and, by the end, he had Elneny in the middle of his three-man defence, Sead Kolasinac – a substitute – in front of the left wing-back, Monreal, and Özil roaming as a false nine.

The new signing from Manchester United, Henrikh Mkhitaryan – who was cup-tied – watched from behind the bench. Wenger had been asked on Tuesday where he intended to play him. “Centre-back, on the right,” he began. On this evidence anything is possible.

It was difficult to fathom, at times, but it worked. Arsenal deserved to progress to Wembley for a 10th time in four seasons – they have won each of the previous nine – and they never looked as though they would surrender the advantage that Xhaka gave them. Willy Caballero, the Chelsea goalkeeper, came up for a last-gasp corner but it came to nothing.

Eden Hazard apart, Chelsea were off-colour and their cause was not helped when Willian felt his hamstring on the half-hour and was forced off. Conte suggested that the problem was not too serious but he launched into a post-match speech about the pressures on his small squad. These kind of injuries, he suggested, were the result of players playing too much.

Where were the reinforcements from the transfer market? Conte’s frustration was obvious and, he continued, the situation was not an overnight phenomenon.

“It is the same from the summer,” Conte said. He went on to lay the blame at the club’s board. They decided on every player, he said. “For sure, I don’t have a big impact on the transfer market,” he added. Conte’s future at Stamford Bridge is already in doubt. This felt like him picking an argument.

The tie had crackled to life at the outset, with Chelsea pressing and Arsenal making mistakes. Alex Iwobi and Shkodran Mustafi erred with loose passes and the home crowd howled. Pedro had a fifth-minute header correctly disallowed for offside before he sent Hazard through and the forward beat David Ospina.

Quick guide Chelsea player ratings Show Hide Willy Caballero A smart save to deny Wilshere but hardly diligently protected for both of Arsenal’s goals. 6/10

César Azpilacueta Tried to organise those around him at the back but sketchy by his high standards. 6 Antonio Rudiger Befuddled, argumentative, tense and involved in both Arsenal goals with inadvertant touches. 5 Andreas Christiansen Detailed with a marking job on Lacazette, the young Dane was the calmest of Chelsea’s defenders. 6 Victor Moses An uninspiring display, booked for a late challenge before he was withdrawn for Zappacosta. 5 N'Golo Kante Tried to make Chelsea tick from midfield, the metronomic presence which kept the ball moving. 6 Tiémoué Bakayoko A performance that was more about force than finesse. Outmanouevred by his opponents too easily. 6 Marcos Alonso Dominant down his flank initially, then increasingly pegged back as the game’s pendulum swung. 6 Willian: Dragged a good opportunity wide before limping off in the first half to be replaced by Barkley. 6 Eden Hazard Leading the strikerless line, he opened the scoring with confident ease. Chelsea’s best faded. 7 Pedro Dinked the ball in the net but had strayed offside, a clever pass for Hazard’s goal. 6 Subs Danny Drinkwater, Barkley (replaced Willian 30, 4), Davide Zappacosta (replaced Moses 72, 6), Mishy Batshuayi (replaced Pedro 66, 5), Gary Cahill, David Luiz, Eduardo.

Arsenal responded. Caballero blocked from Wilshere and then pawed the ball clear of the onrushing Monreal before Rüdiger suffered his first moment of misfortune. Monreal’s header from Özil’s corner hit Marcos Alonso before ricocheting off Rüdiger and flying past Caballero.

Conte described the loss of Willian as “decisive”. It led to a debut off the bench for Ross Barkley but Conte made the point that the January signing, bought from Everton for £15m, was not yet fully assimilated. It was Barkley’s first appearance since last May and Unsurprisingly, he looked off the pace.

The attacking options of both teams were under the microscope. With Arsenal pushing hard to sign Pierre-Emerick Aubameyang from Borussia Dortmund, Lacazette needed a big game but he was restricted to feeding off scraps.

On Chelsea’s side it remains plain that Conte does not trust Michy Batshuayi. With Álvaro Morata injured he preferred Hazard as a false nine. Meanwhile the club’s target, Edin Dzeko, played for Roma and he scored a last-minute equaliser against Sampdoria.

Xhaka and Özil went close before the interval while Hazard slipped as he ran through early in the second half. Iwobi might have made the closing stages more comfortable for Arsenal had he finished from Özil’s cross on 76 minutes but Wenger’s team had done enough.