Well I don’t think many Arsenal supporters saw that coming.

Arsenal were sensational. If we’re going to slate them for being awful when we get a poor result, we have to praise them when they get an excellent win – and that’s exactly how it was yesterday against Manchester United.

The league leaders were blown away and we fully deserved it. The team which were top of the Premier League looked completely lost as we attacked time and time again – if you wanted to be picky you could argue that Arsenal should have scored 5 or 6 goals at least.

Alexis Sanchez was, well, Alexis Sanchez. There are no more superlatives to describe the guy – he is simply outstanding and we are blessed to have him in an Arsenal shirt. He makes the extraordinary look simple and he is truly a world class player.

Mesut Özil looked excellent as well, although he had chances to score a second goal in the 90 minutes. Özil needs to put in a top class performance week in, week out, if he wants to help Arsenal win the biggest trophies. Is this his season? Only time will tell.

But the most encouraging performance for me was from Theo Walcott.

The main striker role is the position we were having the most problems with as it was clear that Olivier Giroud is good to an extent, but doesn’t perform in the biggest games and fails to make the difference when we really need him. The Monaco home game last season was a match with summed up his talent – tries hard but doesn’t have the quality to score enough goals or get us to win the big games.

But with Theo, the signs are promising.

In the last 10 seasons this is the first where Theo has been given a starting berth as Arsenal’s main man. We only have one main striker and he has been given the chance by Arsene to prove he can make it there – and at the moment, he is doing excellently.

Walcott has been criticised for not having a football brain but this season he has shown he has the ability to adapt. Already in this campaign, his hold up and link play has improved dramatically, and his football intelligence has improved ten fold.

He brings others into play, can find a decisive pass and although he didn’t score yesterday, still has an eye for goal. If you want to be super critical you could say his finishing could improve, but don’t forget he is still relatively new to the role.

Like against Leicester last week, he was excellent again against Manchester United. His link up play was good and he made two assists – one for Özil and one for Sanchez. His movement off the ball has improved a lot and his overall game is much much better than before.

He obviously has the blistering pace and the way Walcott, Sanchez and Özil were passing the ball between themselves was mesmerising at times yesterday. And if they are that impressive in early October how are they going to be once they get used to each other in a few months time?

There has to be no doubt whatsoever that Theo is Arsenal’s main man this season – and the bottom line is our title challenge this season relies on his performances.

We all know that Olivier Giroud is not good enough to lead Arsenal to a title, but with his improving performances and adaptation to the role, Theo Walcott is.