Anatomy of a Goal: How Arsenal can be exploited down the flanks

Arsenal embark on their Champions League journey today in Germany, kicking off the competition with a match against familiar foes Borussia Dortmund.

Dortmund, ravaged by injuries to some of their best players, will be forced to field a weakened lineup. With a reduced squad, Jurgen Klopp will hope his side can take advantage of even the slightest opening against the Gunners. Arsenal's draw with Manchester City this past weekend may provide some insight into how they can accomplish just that.

The need for aggressive fullbacks that can get forward and create - or even finish - opportunities is paramount in the game today, and Arsenal are a prime example of that theory in action.

Sometimes, though, that willingness to get up the pitch comes back to bite you at the other end. That is precisely what happened to Nacho Monreal in Saturday's 2-2 draw against the Citizens.

With Alexis Sanchez in possession and taking on defenders, Monreal bombs forward and finds himself at the top of the opposing penalty area. Incredibly, only Sanchez and lone striker Danny Welbeck are more advanced than him at this point.

When Sanchez is tackled, the ball pops out to the halfway line, where Mathieu Flamini, also at fault in this sequence, is unable to win it cleanly against Sergio Aguero. His attempted slide tackle results in the ball ricocheting into the area vacated by Monreal, allowing Jesus Navas to use his pace, keep it in play and run into the acres of space in front of him.

Despite City breaking at pace, Arsenal are still in good defensive position at this point. Aaron Ramsey and Laurent Koscielny are converging on the ball carrier (Navas), while Flamini is marking Aguero in the middle. If the Frenchman were to stay between Aguero and his own goal, he would be able to effectively clear any ball played into the penalty area.

But when the Argentine striker makes his run, Flamini falls asleep at the wheel.

Aguero is able to get behind him and slot the ball beyond 'keeper Wojciech Szczęsny. Just for fun, take a look at where Monreal is at the time of the goal. 

Part of the problem here is simply personnel. Monreal is limited in what he can do - there is a reason he's not the first-choice left-back.

Another issue, though, could be tactical.

Compare this with the system employed by both Spain and Barcelona, and there seems to be a simple way for Arsene Wenger to rectify the issue - though when applied to Arsenal it does have some issues, as we will see.

With Sergio Busquets in the squad, both the Spanish club side and the national team are able to get their fullbacks forward while not exposing their center-backs and leaving them with acres to cover between the two of them.

This, from the 2006 World Cup final, still very much applies to both teams today. When in possession, Busquets (yellow circle) drops deep between the two central defenders, allowing them to split out wide. This creates, essentially, a three-man defense and provides ample cover on the flanks for the fullbacks, who have pushed up into attacking positions.

[Courtesy: Zonal Marking]

Whether Arsenal could utilize something similar remains questionable. Flamini, despite being a willing runner who will never shy away from a tackle, is not as responsible tactically as the unheralded Spaniard - for evidence, simply revert back to the goal above and watch him fall asleep to allow Aguero in.

With Mathieu Debuchy now expected to miss somewhere in the realm of 2-3 months with an ankle injury, Calum Chambers will slot in on the right side. While a lesser player going forward, his time as a center-back should make him more cognizant of his defensive duties, which, ideally for Arsenal, would make him less likely to be caught high up the pitch.

Meanwhile, Kieran Gibbs replacing Monreal on the left side is an upgrade in every way. That said, he too likes to get forward - as any fullback should - meaning the situation outlined above could come up again, regardless of who is on the pitch for the Gunners.

Borussia Dortmund, a notoriously brilliant counter-attacking side under Jurgen Klopp, are devoid of their greatest threat following the injury to Marco Reus. With Arsenal expected to dictate possession tonight, it will be interesting to see if Henrikh Mkhitaryan and Kevin Grosskreutz - likely to start on the wings - will be able to exploit any space in the same way that Navas did on the weekend.