Arsenal shatter Reading FC's FA Cup dream with extra-time victory at Wembley Stadium

But a howler by goalkeeper Adam Federici in the 105th minute gifted Arsenal a lead for the second time that they would not relinquish.

It was a devastating blow for Federici who had been magnificent throughout the club's first semi final for 88 years.

But the Aussie stopper failed to make a routine save from Sanchez's effort with seconds remaining in the first half of extra time.

The pain and disappointment was etched across Federici's face and he had to be consoled by boss Steve Clarke at the final whistle.

Yet every Royals player can feel proud of their superb performance on the day against one of the top sides in the Premier League and Europe.

Gunners, who are attempting to retain the trophy, were in stunning form before kick-off having won their last eight fixtures in the top flight and 16 of their last 18 in all competitions.

Royals, on the other hand, had picked up a mere one victory in their last 10 Championship outings.

Nevertheless, sitting back was clearly not an option for Clarke who boldly named an attacking line-up which included Pavel Pogrebnyak, Hal Robson-Kanu, Jamie Mackie and McCleary.

But against the Gunners' mega-money set-up they were still overwhelming underdogs, with bookmakers offering up to 10-1 on a blue and white victory.

However, it was Royals who looked the more dangerous in the opening minutes with Jordan Obita testing Wojciech Szczesny with a 20-yard piledriver.

Then Mackie was wrongly flagged for offside as he chased a ball over the top and was clean through on goal with only Szczesny to beat.

Gunners, though, had also threatened and it took a smart reflex save from Federici to keep out a Per Mertesacker header from a corner.

And Federici was relieved to see a stunning 30-yard Mesut Ozil free-kick fly an inch wide of his far post before Santi Cazorla fired over the bar.

But Reading were giving as good as they got and Mackie clipped the outside of the Gunners' post on 26 minutes after Szczesny had saved his initial shot.

Mackie was, this time, rightly flagged for offside in the build-up, but it showed that Arsenal's defence looked shaky when put under pressure.

Sadly, Royals fell behind six minutes before the break with half time in sight.

Ozil picked out Sanchez with a clever lobbed pass and the Chile striker killed the ball with one brilliant touch before slipping it through Federici's legs and into the back of the net.

Gunners fans – who had been quiet until that point – suddenly found their voice as Wembley erupted in red and white celebrations.

But their lead was short lived as Royals burst out of the blocks after the break and levelled nine minutes into the second half.

With Reading players pouring forward, Pogrebnyak got to the byline and clipped over a cross.

McCleary had lost it marker and his sweet first-time volley from 12 yards out was too hot for Szczesny to handle as the ball crept over the line, sending 33,000 Royals fans wild.

Clarke's men were deservedly level, but they were having little luck on the day as Pogrebnyak beat the Gunners' offside trap only to receive an incorrect flag.

Then on 65 minutes Robson-Kanu's cross clearly hit Mathieu Debuchy's hand in the box, but referee Martin Atkinson waved play on.

Arsenal hit back and almost regained the lead from a corner when a powerful header by substitute Gabriel was brilliantly clawed away by Federici.

And the same Arsenal player went close again on 73 minutes when his header from eight yards out from a free-kick flew over the bar with the goal at his mercy.

But Reading refused to let their heads drop and continued to ask question of the Gunners' back line with Pogrebnyak dragging a shot wide of Szczesny's far post with 17 minutes of normal time remaining.

It was clear neither side fancied extra time and chances came thick and fast as the game opened up.

Chalobah nearly fired Reading ahead with a low piledriver which Szczesny was happy to push around the post.

Then with six minutes left Ramsey hit the woodwork from barely six yards out with only Chris Gunter back on the line after Federici had saved the Welshman's initial shot.

If that was a lucky escape for the Royals, they blew a gilt-edged chance to take the lead three minutes later.

Pogrebnyak and Mackie launched a two-on-one attack with Gabriel as the only Arsenal defender to beat.

But the Russian held on to the ball too long and his tame shot was easily held by Szczesny when Mackie was unmarked and screaming for the ball.

It was the last clear-cut chance during 90 minutes as a nailbiting semi final moved into extra time.

Suddenly, opportunities began to dry up as fatigue began to take its toll on both teams.

However, the Gunners almost scored a second goal in the 103rd minute when Ramsey's 25-yarder struck Federici's body and bounced just over the crossbar.

But two minutes later they did put the ball in the net after an awful error by Federici.

There looked to be little danger when Sanchez cut in from the right and his angled shot should have been easily gobbled up by Federici.

But the Aussie stopper allowed the ball to squirm through his body and over the line.

It was so harsh on the Reading goalkeeper who had made a string of outstanding saves during the game and looked at his very best.

Wenger's men, though, grew in confidence and only the width of the post prevented Giroud from scoring a third with eight minutes to go.

Yet the north Londoners held on over the closing stages to deny Reading a place in the final.

Reading FC: Federici – Gunter, Pearce (c), Hector, Obita – McCleary, Williams, Chalobah (Cox 105), Robson-Kanu (Karacan 90) – Mackie – Pogrebnyak. Subs not used: Andersen, Cooper, Kelly, Norwood, Yakubu. Booked: Chalobah 45.

Arsenal: Szczesny – Debuchy, Mertesacker (c) (Gabriel 63), Koscielny, Gibbs – Coquelin (Walcott 101), Cazorla – Ramsey, Sanchez, Ozil – Welbeck (Giroud 72). Subs not used: Ospina, Monreal, Flamini, Wilshere. Booked: Gabriel 107.

Referee: Martin Atkinson.

Attendance: 84,081.