Arsene Wenger accepts he needed to freshen Arsenal up to reach FA Cup final, Manchester City far from finished artcile

Five things we learned: Alexis Sanchez forced home the decisive goal in extra time to relieve the pressure on Arsene Wenger and book another date at Wembley

Alexis Sanchez struck from close range to send Arsenal through to meet Chelsea (Getty)

Arsenal progressed to this year's FA Cup final after coming from behind to beat Pep Guardiola's Manchester City in extra-time at Wembley.

Arsene Wenger's men were put on the back foot when Sergio Aguero broke the deadlock in the second half but found an equaliser through the unlikely source of Nacho Monreal less than 10 minutes later.

Alexis Sanchez found the winning goal, bundling home from close range in the 101st minute.

Here are five things we learned from this entertaining semi-final...

Wenger finally trying to freshen things up

Arsene Wenger has been so stubborn to change, be it spending vast amounts of money on players or freshening up methods of motivating his players. However, he again stuck with a back three in an attempt to show that he isn’t a footballing dinosaur, but is still ‘down with the kids’. The three-man defence has worked wonders at Chelsea and Tottenham this season and it appears as though Wenger is willing to try it in order to show the board he is capable of moving with the times. And judging by the result, he may not be done yet.

Wenger is beginning to experiment with a 3-5-2 formation (Getty)

City machine still needs oiling

There was a lot of things right about the way City attacked but they often looked just one tool short of a set. Often it was just a loose pass, an attacker straying offside or a bit of bad luck – but the Pep Guardiola masterplan is still far from complete. At the other end of the pitch Claudio Bravo again failed to instil any confidence in himself remaining as City’s number one goalkeeper. He dropped crosses and looked lost at sea under pressure. Regardless of Joe Hart’s limitations with his feet, surely he is a better option than Bravo?

Bravo flapped at a number of crosses under pressure (Getty)

Loss of Silva

How big will David Silva’s injury be? The Spaniard was replaced by Raheem Sterling and hobbled off down the tunnel. With the Manchester derby on Thursday it could have just been precautionary from Guardiola but the way he gingerly walked off suggested he could miss a chunk of City’s run in, and with their Champions League place far from secured, it could be a time to worry for the blue half of Manchester.

Who would be a referee?

In a five-minute spell there were two huge calls from the referee and his assistants. They got the first big call correct when Laurent Koscielny’s header was ruled out for offside but then came two questionable decisions. Firstly, Sterling thought he’d taken the lead after finishing a disjointed City attack but the linesman incorrectly raised his flag for the cross from Leroy Sane drifting out of play. Next Alexis Sanchez was hauled to the ground as a cross came in after Jesus Navas had his hands all over him. Again, the penalty claims were dismissed and City played on. Two big calls – rightly or wrongly.

Sterling's goal was ruled out after the ball was judged to have gone out of play (Getty)

Aguero sends timely reminder

Sergio Aguero reminded Guardiola of exactly what he is capable of at Wembley, with his superb run and deft chip putting City ahead. The Argentine was dropped earlier in the season after the arrival of Gabriel Jesus and with the Brazilian nearing a return to first-team action, the goal came at a vital time for Aguero.

It is likely to force Guardiola into working out a system where both his strikers can play alongside each other, rather than having an either-or situation. He has been the deadliest striker in England since arriving in 2011 and 17 Premier League goals in what has been considered a quiet season isn’t too bad.