5 Things We Learned from Champions League Week 6

The 16 qualifiers have been finalised, and the group stage of this season's UEFA Champions League is over and done with.

Juventus were perhaps the biggest shock after Galatasaray knocked them out on a dreadful pitch in Turkey in a game that perhaps should not have been played, such was the farcical nature of the spectacle. However, I stress that it was the same for both sides, and Gala just adapted to the conditions better.

Neymar became the first player in history to score a hat-trick in both the Copa Libertadores and Champions League with his treble against Celtic, while Schalke beat Basel in Germany to advance at the expense of the Swiss side. 

And of course, there were numerous talking points elsewhere, not least Kevin Grosskreutz's 88th-minute winner in Marseille, which sent last year's finalists Dortmund into the last 16 at the expense of Napoli.

The action is now put on hold until February and the knockout stages, but here's a look at five things we learned from Week 6.

Defeat in Naples Will Still Harm Qualified Arsenal

Giuseppe Bellini/Getty Images

Despite losing 2-0 to Napoli at the Stadio San Paolo, Arsenal—rather than their hosts—left the field in Naples with a feeling, if not of happiness, then of relief.

However, thanks to those goals from Gonzalo Higuain and Jose Callejon, and more importantly because of Kevin Grosskreutz's late winner for Borussia Dortmund in Marseille, it was a poor night for the Premier League leaders.

For now, having finished behind the German club in the group, Arsene Wenger's side face a far more difficult tie in the last 16 than they could have expected for much of the evening.

"

60% chance of Arsenal heading to Spain in the last 16. The other 40% are Bayern or PSG. Tonight's a nightmare for Arsene Wenger. #AFC

— Alex Richards (@AA_Richards) December 11, 2013"

Rather than Zenit (who qualified with a measly six points), Galatasaray, Olympiacos or a Bayer Leverkusen side that were hammered 5-0 by a Manchester United side in apparent crisis, the Gunners must now do battle with one of the group winners.

The difference in quality is massive.

Thus, excluding United and Chelsea (the two English group winners) and Dortmund (same group), Arsenal will face either Real Madrid, Paris Saint-Germain, Bayern Munich, Atletico Madrid or Barcelona in the last 16.

That's a daunting prospect.

AC Milan in Name Only

Claudio Villa/Getty Images

AC Milan squeaked over the line, but it feels almost wrong to label Max Allegri's current incarnation as "seven-time European champions AC Milan."

For these are a rather miserable Rossoneri.

With four wins from 15 games in Serie A—where they sit some 22 points off the leaders Juventus—they've scraped into the knockout stages with nine points from their six matches, after just about getting past Ajax.

Certainly the sending off of captain Riccardo Montolivo didn't help, but any manager who is studying the tape of Wednesday's draw with Ajax will be delighted to come up against the Milan in the next round.

They allowed Ajax to have 70 percent of possession as well as 25 shots on goal (the last of which, an ambitious bicycle kick, went inches wide). Milan are fortunate that the Dutch side lack that little bit of class in the final third that can kill a team.

The fact that WhoScored's highest-rated player for the game was Christian Abbiati says it all.

That Allegri celebrated so joyously at the full-time whistle tells you just how far they've dropped.

This is a poor Milan side; miraculously, they're the last Italians left standing. Don't expect them to stand for too much longer in the 2013-14 competition.

"

AC Milan: Despite progressing to the knockout stages, AC Milan have not won back-to-back Champions League matches since October 2011

— WhoScored.com (@WhoScored) December 11, 2013"

Bayern Can Be Beaten, but Do They Beat Themselves?

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There is no doubting that Manchester City gave an excellent showing of character in the Allianz Arena to turn the game around and claim a 3-2 win.

But with regard to the result, how much credit do we give Manuel Pellegrini's men and how much blame do we apportion to Bayern Munich?

For what it's worth, I'm leaning closer to the latter.

After 11 minutes, Die Roten were cruising. Dominating the game, they were knocking the ball around confidently. They had a wonderful grace about them and were a delight to watch—as it has been for much of the last 18 months.

And with Thomas Mueller's wonderful first goal and Mario Goetze's second, they were good value for their 2-0 lead.

But as the first half moved on, they showed a complacency in their play. The tempo, sharpness and slickness of their passing dropped, as did the intensity. Jerome Boateng's mistakes didn't help either.

And suddenly, they were 3-2 behind and had been beaten for the first time in a competitive match since their German Super Cup defeat to Dortmund in July.

"

City punished Bayerns complacency, says Mueller - Midfielder Thomas Mueller has admitted Bayern Munich were punish... http://t.co/pC94l9vLPW

— Bayern Munich News (@BayernNewsOnly) December 11, 2013"

In short, it was a similar occurrence to the second leg of their last 16 tie against Arsenal last season, when the job had all but been done with a 3-1 win in the first leg.

They responded magnificently after that by dismantling Juventus and Barcelona in the quarter-finals and semi-finals, respectively.

I suppose fans would settle for a similar response again, but Pep Guardiola must have his side guarding against similar complacency in the future.

"

Bayern Munich losing is not such a bad thing for them. It will wash away any complacency going forward and serve the greater good.

— James D. (@JDTIPS) December 11, 2013"

Spanish Trio in Rude Health

Gonzalo Arroyo Moreno/Getty Images

Three of Spain's four sides have progressed to the knockout stages, and all could have designs on claiming the trophy.

All three have finished top of their group, all three have done so in comfortable fashion, and all will be fancied to make the quarter-final stage.

Real Madrid, currently third in La Liga, have perhaps been the most impressive side in the Champions League so far.

In search of La Decima, they've qualified with more points than any other side (16) bar Atletico. They also have a greater goal difference than any other side (plus-15), and Cristiano Ronaldo is in the form of his life (that's saying something) with nine goals to his name already.

City rivals Atletico have also been ruthless in their dissection of Porto, Austria Vienna and Zenit in Group G, claiming 16 points. They conceded the joint least goals (three) from their six matches, and Diego Simeone's hard-running, outstandingly organised unit are a match for just about anyone in the competition.

And Barcelona, leading La Liga under Tata Martino, have also won their group, taking 13 points from their six matches. While the defensive frailties that were so ruthlessly exposed by Bayern remain, in Lionel Messi (who will hopefully be refreshed come February) they possess arguably the greatest player of all time.

Meanwhile, Neymar is also starting to do more than merely find his feet. Witness his wonderful treble against Celtic.

Additionally, they know how to reach the last four, having done so in the last six seasons.

All in the Spanish trio have been rather excellent.

"

Difference between top 3 in Spain & rest evident in CL too. Barca, Real, & Atletico a combined P 18, W 14, D 3, L 1, F 51, A 13

— Kieran Canning (@KieranCanning) December 11, 2013"

Good luck to whichever second seeds have to face them—it's not a task that any side, even Arsenal, should relish.

Zenit: The Worst Qualifiers Ever

Epsilon/Getty Images

Zenit St Petersburg have made a record of their own in qualifying for the knockout stages.
Luciano Spalletti's Russians have become the first side to qualify with just six points and a minus-four goal difference. 

What happened in their final group game when only victory would guarantee their place? A 4-1 defeat to Austria Vienna, who had taken only two points from their five group games.

"

FACT: @Zenit_spb have qualified with only 6 points which is a record low. Previous lowest was 7pts by 7 different clubs. #UCL

— Champions League (@ChampionsLeague) December 11, 2013"

UEFA Cup winners in 2008, Zenit haven't done too badly in Europe in recent years; however, given the money they've spent on talent—Danny, Hulk and Axel Witsel to name but three, and all of whom remain—perhaps they should have done better.

But now group winners will look forward to meeting this side come the draw.

They are defensively cumbersome no matter which centre-half pairing plays, over-reliant on the inconsistent Hulk and awful travelers in the Champions League proper, with just two wins in 10 away fixtures. No wonder other teams will be chomping at the bit to play them.

Twitter: @AA_Richards