A calamitous error from goalkeeper Adam Federici caused extra-time heartbreak for Reading and sent Arsenal into the FA Cup final for the second successive season. Having been a big part of Reading ensuring that it was another uncomfortable Wembley visit for Arsenal, Federici let Alexis Sanchez’s tame shot squirm through his hands and trickle over the line to put the high-flying Premier League side back in front just before the end of the first half of extra-time.

This time a spirited and well-drilled Reading side had no answer. But a team languishing in the lower reaches of the Championship earned plenty of plaudits after shaking off the disappointment of going behind to Sanchez’s expertly taken goal late in the first half. In a far more open second period, Reading quickly equalized through Gareth McCleary and will feel that they should have had a penalty when Mathieu Debuchy handled a cross from Hal Robson-Kanu. Arsenal, of course, still dominated possession, but they couldn’t find a way back in front. Federici more than did his bit in keeping his side level, and initially saved well from Aaron Ramsey when one-on-one before the Arsenal midfielder struck against the post after the ball fell back into his path. But instead of a day to savor for the experienced Australian, it will be one that he will be desperate to forget.

His blunder means Arsenal will now get a chance to retain the FA Cup back at Wembley next month against either Aston Villa or Liverpool. But, on a day in which Chelsea beat Manchester Untied to surely end any hopes of an active title race, all the optimism that has been built up around the Emirates Stadium after eight successive wins, was so nearly emphatically destroyed. For all the strides they have made, this was, on the back of a shootout victory over Wigan in last year’s semifinal and an extra-time win over Hull City in the final, another unconvincing Arsenal performance in a high-pressure game they were expected to win.

Still, win they did. And they now stand on the verge of becoming the most successful club in the FA Cup’s history, with a 12th win now in their sights. For a time it looked like they were going to produce the convincing win expected of them. In contrast to last year’s semifinal against Wigan, Arsenal began with more purpose and urgency. And they had two chances to get the early goal they will have dearly craved. Danny Welbeck failed to make the most of an opportunity when getting in behind the Reading defense, while Per Mertesacker had a near-post header from a corner well saved down low.

Reading were unsurprisingly set up to try and frustrate their in-form opponents, meaning they had little possession of their own. Their only sight of goal through the first 45 minutes came when left-back Jordan Obita arrived on the end of a cross on the edge of the box, but failed to seriously test Wojciech Szczesny, again chosen instead of David Ospina to start in the FA Cup. Reading manager Steve Clarke will have minded little about his team’s lack of attacking endeavors as long as they continued to restrict Arsenal.  

But those plans fell apart when his side’s focus slipped six minutes before the interval. Mesut Ozil was allowed the luxury of yards of space to pick a pass in the final third, and he produced one of his usual high quality to find the run of Sanchez in behind a dozing Reading defense. From there, there was little doubt that the Chilean would do the rest, chesting down and fainting past McCleary before finishing clinically low into the corner of the net.

The stage was set for Arsenal to go on and firmly take charge of a game in which Reading’s need for a goal would doubtless open up space for the Premier League side to exploit. Instead the familiar fragility that has so often undermined Arsenal’s ambitions in recent seasons reared its head to help Reading get right back into the fixture.

Less than nine minutes of the second half had been played when Arsenal went to sleep from a throw-in down their right side, and Pavel Pogrebnyak crossed from the byline. McCleary’s effort at the back post deflected off Kieran Gibbs to deceive Szczesny and clearly cross the line before Arsenal’s keeper could rescue it.

Reading continued to cause Arsenal alarm in their rare forays forward and Arsene Wenger’s side were desperately fortunate to avoid conceding a penalty. Arsenal had their chances, too. Substitute Gabriel Paulista twice had free headers in the box, but saw the first spectacularly save and the second go high over the crossbar. With seven minutes of normal time remaining, Arsenal really should have sealed their progress. Ramsey, played through by the recently introduced Olivier Giroud, was denied by Federici and then blasted against the woodwork with the goal at his mercy. Giroud, himself hit the post in extra-time, but by that time the game’s defining moment had already left Federici red-faced and Arsenal hugely relieved.