Arsenal's impressive 2-0 win over Bayern Munich on Tuesday night showcased their ability to perform when it really counts, but also highlighted a lack of focus as their ultimate weakness.
Arsene Wenger admitted that the Gunners were more focused on the Premier League during losses to Dinamo Zagreb and Olypmiacos in the Champions League recently - an utterly wrong approach to take when it comes to Europe's biggest competition.
Playing David Ospina over Petr Cech has often been cited as the reason behind said losses, but Wenger's men should be winning both games even with Ospina in goal. Blaming the Columbian's inclusion is ridiculous.
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Complacency should be blamed. The players expected to win before the games had even begun.
After beating Bayern, Arsenal will rue their two embarrassing losses - the Gunners could be at the top of Group F, rather than bottom.
Unfortunately, it now seems the best possible outcome would be a second-placed finish and a tough last 16 tie against a group winner. This wouldn't be a new experience for the north Londoners, of course.
It seems ridiculous to think that a team of Arsenal's pedigree and success can play with such a naive attitude one minute, but then produce such a defensive masterclass against one of Europe's best the next.
They knew what was at stake, and now they could suffer the consequences of not progressing through to the last 16, instead challenging in the Europa League - something that could hamper their Premier League ambitions.
The Gunners were guilty of such naivety in the Premier League during their first game of the season, in the 2-0 loss to West Ham at the Emirates.
Wenger seemed to assume that because his players were better they would just take to the field and secure a comfortable win. The Hammers, though, had different ideas.
The Frenchman almost predetermined how his side would play in future weeks when he discussed his team's inclination to burst forward and disregard the basics following the unprecedented defeat.
He said: "I felt we were a bit nervous and we rushed our game a bit. We didn’t always respect the basics. We wanted to be too quick going forward in first half."
Arsenal's problem has always been their ability to comfortably dispatch the lesser teams and struggle against the elite - this season, however, is the complete opposite. They've discovered the formula to beating the best - now, they must remember how they conquered those below them.