Is the Premier League's reign over?
Is Lionel Messi the greatest ever?
Did Arsenal inspire a top-three finish?
With both Champions League and Europa League fixtures this week, football fans were treated to some truly exciting football.
There were more than a few surprises.
Here are 10 things we learned.
Perennial contenders for half the season and clear pretenders for the other half.
Such is the story of Arsenal in the last few years.
Less than a month ago we saw Arsenal look like a second division club against Milan.
Then Milan came to London and looked unworthy of even sharing the pitch with Arsenal for a half.
Milan may not have been at their best due to complacency and a comfortable lead, but we cannot deny that Arsenal looked nearly unstoppable for 45 minutes.
If Arsenal could match that form for an entire season, they could actually compete for a title again.
La Liga rightly gets criticized for being a two-horse race.
But Barcelona and Real Madrid's dominance doesn't mean that Spain is devoid of talented clubs and some of Europe's best coaches.
Unai Emery's Valencia will regret giving up two late goals to PSV, but still completely outplayed the Dutch side. Roberto Soldado provided two more reasons that del Bosque should make him Spain's target man this summer.
Marcelo Bielsa's Lions proved to have the better midfield, better attacking movement, and better fitness. If not for one of David de Gea's better matches, Bilbao may have left England with a five-goal lead.
Iker Muniain, Ander Herrera, and Javi Martinez showed England's best that Bilbao is a club for the future.
None of these players is even in his mid-twenties yet. Europe is not short on young talent and that means great things for the future.
In the first half of the season, some fans were claiming Manchester was the new mecca of football and both clubs took turns being labeled the best in the world.
Now that we've seen them compete with other clubs in Europe, we know better.
Both clubs continued their disappointing European form by losing in the Europa League.
While most will expect City to rebound with a win at Etihad, United looks to be in much more trouble.
A late, helpless penalty made the score from the United-Bilbao match look much closer than it actually was. Atheltic Club simply outclassed Manchester United.
For Manchester to truly be one of Europe's best footballing cities, both clubs will have to do much better outside of the PL than they have this season.
It would be hard for anyone not to cheer for APOEL.
The Cyprus club surprised everyone when they finished top of their group and continued their magical run by outlasting Lyon on penalties to move into the Champions League quarterfinals.
If APOEL can get a favorable draw in the next round, they have a decent shot of sending this record-breaking club even deeper into the tournament.
The idea of such a relatively unknown club making the semifinals of Europe's greatest tournament is great for football and its fans.
Two of the best leagues in the world, the Premier League and Bundesliga have been very disappointing in Europe this year.
Borussia Dortmund crashed out in the group stages of the Champions League. Bayern Munich lost to Swiss side Basel.
That trend continued this week.
In addition to both Manchester clubs losing, Arsenal failed to progress despite their best efforts. Schalke could not hold off Dutch side, Twente.
Most shamefully, though, was Bayer Leverkusen.
Perhaps they were so concerned with getting Messi's jersey this time around that they forgot they were supposed to stop him.
They ended up giving up seven goals to Barcelona in one of the most lop-sided matches in history.
As for Lionel Messi...
Have you ever played a sports video game and created a player with perfect ratings?
Lionel Messi is the closest thing to the real-life version of that.
Messi further cemented his status as the best player in the world by single-handedly carrying Barcelona to a record-setting victory.
He became the first player in Champions League history to score five goals in a single match.
Argentina coach Sabella said it best when he called for a new adjective just for Messi.
The Argentinian simply embarrassed Bayer Leverkusen and sent a message to the rest of Europe, reminding them that Barcelona is the best club in the world until someone proves otherwise.
Unlike the English, Italians, and Germans, Spain and Portugal's clubs made a clean sweep this week.
Barcelona, Valencia, Atletico Madrid, Athletic Bilbao, Benfica, and Sporting Lisbon all won their European matches.
Some of those victories came against favored opponents.
While only time will tell how many of these clubs advance to the next round, it is clear that, at least for the moment, the best competition in Europe is on the Iberian Peninsula.
Serie A has slowly rebounded from the 2006 cheating scandal that rocked the footballing world.
Despite the setback, the league has done rather well in Europe, most notably with Inter's Champions League win two years ago and Napoli's CL run this season.
Still, Serie A is not quite ready to compete with Europe's elite.
Inter has spent half almost the season fighting relegation. Juventus just cannot take that final step.
No disrespect to Napoli, but when they look like the league's best shot at European glory, the league is not quite as strong as it wants to be.
Perhaps Milan can prove doubters wrong and lift the CL trophy once again.
Fans of either Manchester club may disagree, but it is great for European football that both clubs failed to progress in the Champions League.
Their presence in the Europa League allows fans that would not normally get to watch them play their favorite club or see them live to do so.
It also gives more clubs a chance to measure themselves against two of the world's best.
It is not just the competition that is benefiting, though. So are the English clubs and fans.
Just this week, Manchester United and Premier League fans who do not closely follow La Liga saw just how good Spanish clubs are.
Without consistently watching La Liga, the average PL fan would fail to recognize the talent at Bilbao. They would not enjoy the beautiful attacking football that Bielsa has created.
Those fans would also not be open to watching other Europa League matches.
For that reason - and due to so many great clubs still being in the tournament - the Europa League will challenge the Champions League this year for being the most enjoyable tournament.
While the CL is the more prestigious and respected tournament, that does not mean the the Europa League cannot be more exciting.
What are your thoughts?
Are there any points I missed that should have been include?
What did you take away from the European matches this week?
Feel free to leave your feedback below.
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