Bayern Munich beat Wolfsburg on Friday night to continue their elegant stroll toward the Bundesliga title.
What's worrying for Arsenal is that they did it in second gear—Jupp Heynckes had his team take it easy while simultaneously resting the likes of Javi Martinez so they could recover.
Nevertheless, we can gain some understanding from the tie, and how Wolfsburg played will give the Gunners valuable lessons as Tuesday's date approaches.
Wolfsburg set out in a defensive, counterattacking 4-2-3-1 formation and pressed high up the pitch to try to make life difficult for Bayern Munich on the ball.
There was one notable exception, however, in Daniel Van Buyten. Every time he collected the ball, die Wolfe simply waited for him to pass it. Dieter Hecking wasn't worried about the Belgian's passing ability, but he was worried about what Dante can do. No pressure on DVB at all.
Ignoring a non-threat allowed them to focus their numbers in man-marking throughout the pitch without becoming too stretched, and it's a tactic Arsenal could well use themselves.
Vierinha (VfLW winger) tussling
The threat of Philipp Lahm and David Alaba coming forward (and the fact that they can actually defend) is something Bundesliga teams have to negotiate on a regular basis.
The free-flowing movement in Bayern Munich's system is unbelievable, and with Mario Mandzukic's mobility and ability to play wide and interlink, it's easy to see how he displaced Mario Gomez.
When die Bayern get going, it's scary for defences.
Wolfsburg used wingers in Vieirinha and Ivica Olic—two players with incredibly high work-rates—to try to track the full-backs all the way to their own touchline, meaning Bayern would struggle to create a numbers overload on one flank.
It helped a little.
A team like Bayern Munich will stretch you in many ways, but they're at their most dangerous when they go wide.
Mario Mandzukic has forged a great understanding with Thomas Mueller, and when the striker drifts wide to create a three vs. two on the right, Mueller is usually able to get to the byline and meander inside.
This is when football gets messy, as slight movements from attackers can free you from markers and create new angles. Mueller is one of the best in the game at creating this chaos and picking the pass, while Franck Ribery isn't too shabby either.
If Arsenal ever had a succession of coaching sessions where defensive positioning was critical, this is it.
Franck Ribery is in the form of his life right now.
Not only does he track back and carry out defensive duties we've rarely seen him commit to in his career, he's still mercurial going forward and has one of the quickest pairs of feet around.
He's a yellow-card magnet—a foul waiting to happen.
His ability to win free kicks near the penalty area is one of the reasons Bayern's defenders enjoy so many attempts on goal, and with Arsenal's fragility in defence, the full-backs are going to have to be so, so careful.
You don't want Mario Mandzukic, Daniel Van Buyten and Dante constantly shuffling into your box for set pieces.
Diego playing for former club Werder
In Wolfsburg's 4-2-3-1 formation, Diego was deployed as a playmaking No. 10 behind striker Bas Dost.
Unfortunately for the home side, they were barely able to get him the ball, and he barely troubled Bayern Munich's holding-midfield pivot.
Playing someone in the No. 10 role against die Bayern is suicide unless they're going to work their socks off—play hard or go home.
Diego as a passive No. 10 was useless, a non-factor. Whoever Arsene Wenger deploys furthest forward must be prepared to chase, harry and perhaps not see as much of the ball as they would against Sunderland or Aston Villa.