Saturday's 5-1 defeat to Liverpool was not the first time Arsenal have had a setback this season.
There have been three moments in this campaign when they've fallen short at important times, and on each occasion they've responded well. So much so that they've spent more time top of the Premier League table than any other club.
Setback 1 - Arsenal 1-3 Aston Villa: Aug. 17, 2013
The opening day of the season. Despite unquiet about the lack of action in the transfer market, there is genuine optimism that the season can start with a win. Ninety minutes, some awful refereeing and three Aston Villa goals later, the Gunners have lost at home.
The reaction is visceral, vicious and almost unprecedented. The pressure on Arsene Wenger and his team is huge.
The reaction: Arsenal win their next 10 games in all competitions and remain unbeaten in the league until they head to Old Trafford.
Setback 2 - Man Utd 1-0 Arsenal: Nov. 10, 2013
Having been on such a good run and facing a United side playing well below par, there's real belief they can get a win at Old Trafford for the first time since 2006. Instead, a Robin van Persie goal is enough to sink a flu-stricken Gunners.
The reaction: Arsenal win their next three Premier League games, not conceding a single goal in the process. Which leads them to:
Setback 3 - Man City 6-3 Arsenal: Dec. 14, 2013
A disastrous day defensively sees a rampant Man City score six. Despite the fact Arsenal score three of their own, questions are asked of their title credentials.
The reaction: Six wins, two draws, five clean sheets. A run that saw them top the table until Saturday.
The defeat to Liverpool raises some serious questions about this Arsenal team. In the big away games, they've been found wanting to various degrees. Spanked in Manchester and Liverpool and sucker punched by United, results like that make people wonder if there's an inability to win games when the pressure is high.
Arsenal had a chance to make a real statement of intent at Anfield, and they singularly failed to do so. It's why there's scepticism about their title challenge. Until they perform and get a couple of good results in games like this, those doubts will linger.
- Kelly: Tempo key to Anfield master class
- McNicholas: Arsenal collapse damages credibility
- Brewin: Three Things: Liverpool vs. Arsenal
However, Arsenal have also shown this season that when the setbacks arrive they have the character to deal with them. Each disappointment has been followed by a run of excellent results, and Wenger needs to see that again from his team.
Beating Manchester United at home would go a long way to putting the disappointment of Anfield behind them. While Saturday's result might show that this Arsenal team is capable of capitulating in a big way from time to time, a win at home on Wednesday would illustrate its ability to react in the most positive way possible.
With cup adventures against Liverpool and Bayern Munich to come inside the next 10 days as well, Arsenal have to get themselves back on track as quickly as they did previously this season.