Arsenal's luck was well and truly out at Old Trafford yesterday. Despite looking the far better team for most of the ninety minutes, they hit the bar, had a goal disallowed, were on the wrong end of some rough refereeing decisions and, essentially, gifted United the game with two stupid mistakes.

We were looking for a sign from this team that they are ready to take a step up and prove themselves to be true contenders this season and, for the most part, we got it. Without Cesc Fabregas, the squad's single-most influential player, the Gunners turned in an outstanding performance. They took the game to United, passed the ball better than their hosts and, overall, looked the far more fluent side.

A positive first-half display was capped with a breathtaking goal from Andrey Arshavin to give the Gunners a deserved lead at the break. Only seconds after being denied the stoniest of stone-wall penalties, the diminutive Russian pick up the ball 25 yards from goal and unleashed a fierce drive that Ben Foster in the United goal saw late and couldn’t keep out.

Arsene Wenger’s men started the second half with their tails up and had United on the ropes. The turning point of the match arguably came in this period when Foster made a desperate but brilliant save with his foot from Robin Van Persie. Had the Gunners gone two up at that point, one sensed that the three points would be theirs. As it was, in the 59th minute Wayne Rooney chased a diagonal pass into the penalty area. With the ball heading away from the goal, Manuel Almunia rashly dived at Rooney’s feet and the United striker was only too happy to go down under the slightest contact to earn a penalty. Having been the fortunate recipients of a similar decision on Wednesday night, Arsenal fans could not really complain about the outcome. What was frustrating though was why Almunia felt the need to over-commit himself when the United player had lost control of the ball and was heading towards the corner.

Frustration turned to disbelief five minutes later when, completely unchallenged, Abou Diaby headed a Ryan Giggs freekick into his own net. What was he thinking? I am not even sure he knew. Why, when he was under no pressure, did he presumably elect the ball out for a corner instead of heading it away from goal? It was the sort of poor decision-making that leaves plenty of question marks over Diaby’s true potential. It has often been noted in this column that he looks at his best when Arsenal are on the break but when the team are defending he is a liability. That observation was cruelly underlined yesterday. Overall, he turned in a pretty substandard performance and his catastrophic mistake will hardly help convince those who have their doubts about him. After notching up two goals against Portsmouth, Arsene Wenger likened him to Patrick Vieira but such comparisons are not likely to hold much water until he starts delivering big performances in big matches rather than producing occasional good displays against dire opposition.

Arsenal’s day of exasperation was completed in injury-time when Robin Van Persie netted what seemed to be a last gasp equaliser only to have the goal ruled out for offside in the build-up. The replay later proved the decision was correct but it was still a blow for the Gunners after they had been on the wrong end of many of the refereeing decisions throughout the game.

Six Arsenal players were booked in a match that, whilst being highly competitive, never spilled over into blind aggression. The roughest justice meted out by referee Mike Dean came with the denial of a penalty when Darren Fletcher scythed down Andrey Arshavin in the area just before half-time. How the official could see this as anything other than a penalty beggars belief. All this came on the back of little decisions that had niggled the Gunners throughout the half. For example, how did Antonio Valencia not find his way into the referee’s notebook following three bad early fouls? Also, apart from his blatant foul on Andrey Arshavin, Darren Fletcher made several challenges worthy of a yellow card. He escaped censure and yet Robin Van Persie
got booked for what looked like a perfectly good tackle and Bacery Sagna received the same punishment for complaining about a throw-in. Throughout the afternoon there seemed to be a disparity between what it took to get an Arsenal player carded compared to what it took for a United player to have his name taken.

When considering the performance as whole, there were plenty of good things about the Arsenal display and supporters can take a lot of heart from the fact that the team largely dominated the reigning champions on their own ground. It was a complete reversal of last season’s Champions League semi-final when the Gunners looked entirely second-best in both legs.

Yet again, the new formation worked well with possibly one slight proviso. As talented a player as he is, Robin Van Persie is not suited to playing as lone striker. He is so instinctively left-footed that he is constantly trying to work the ball onto that side. When the team are breaking down the right, this greatly diminishes his effectiveness. A more workable solution might be to allow him to drift out to either wing - where he can work the outside on the left or cut in from the right - and play Nicklas Bendtner as a big target man for the rest of the team to play off. Certainly, one of the Dane’s stronger suits is bringing others into the game and he looks a potentially better option in the lone striker role.

It should also be noted that despite the two errors that led to the United goals, the Arsenal defence looked solid and well-organised. William Gallas and Thomas Vermaelen are starting to build an excellent understanding with the latter in particular producing yet another very impressive display.

What was less pleasing about yesterday’s performance was that the team failed to put Alex Ferguson’s side to the sword when they looked more there for the taking than they have done for years. Unquestionably, Arsenal completely let United off the hook and, consequently, despite the good showing, the result is a massive disappointment.

The Gunners will have the chance to lick their wounds and consider what went wrong over the upcoming international break. Surely though, the key lesson from yesterday’s defeat was that if this team has pretensions of becoming champions they will have to develop a far more ruthless streak and cut down on the individual errors.

In a fortnight, they return to Manchester to take on big-spending City. It will be another stern test and one that the Gunners need to prove they can pass.