The Champions League returns this week with eight group-stage matches Tuesday and eight more Wednesday.
Marquee matchups include Real Madrid's trip to Holland to face Ajax and the battle between English champions Manchester City and German champions Borussia Dortmund.
Here are six key battles to watch in this week's slate of matches. Be sure to add your own to the comments below.
The new season has been unkind to Manchester City's defense.
Through six league matches, Roberto Mancini's team still has not kept a single clean sheet. In the Champions League opener last month against Real Madrid, City allowed three goals, including two in the closing minutes.
That makes defense a priority when Borussia Dortmund visit Wednesday night. Polish forward Robert Lewandowski scored the only goal, a late strike, when Dortmund beat Ajax 1-0 at home in both teams' Champions League opener.
Lewandowski, a big, strong attacker, presents a constant threat, but new signing Marco Reus has been Dortmund's most lethal attacker in the league, having scored four goals.
Stopping both will be key for City.
Our first club in turmoil is Zenit St. Petersburg, the defending champions of the Russian Premier League.
After winning the title again last spring, Zenit and manager Luciano Spalletti invested heavily in the squad over the summer, bringing in Brazilian forward Hulk (pictured) and Belgian midfielder Axel Witsel at the transfer deadline for big money.
But while that initially boded well for Zenit's European prospects, the arrival of those two players has unsettled the team. Midfielder (and former captain) Igor Denisov and forward Aleksandr Kerzhakov were demoted to the youth team after criticizing the team's transfer policy.
Denisov and Kerzhakov—who argued, in essence, that the new players didn't warrant exponentially higher wages than the existing players—might or might not have been right to complain, but now that they have, the team is in chaos.
Our second club in turmoil is AC Milan. After finishing second in Italy's Serie A last season, the Rossoneri sold star striker Zlatan Ibrahimovic and defender Thiago Silva as owner Silvio Berlusconi—yes, that one—tried to balance the books.
To put it simply, Milan haven't been the same since. Three losses early in the league season and a draw at home to Anderlecht in the Champions League have placed manager Massimiliano Allegri on the hot seat.
If Milan lose again this week, he might be gone.
Schalke produced a mild surprise on Match Day 1, beating Greek champs Olympiakos 2-1 away, thanks to Klaas-Jan Huntelaar's second-half winner.
Huntelaar is always dangerous, but the key for Schalke will be closing down Montpellier's creative midfielders.
In Montpellier's first-ever Champions League match, a 2-1 home loss to Arsenal, Younes Belhanda and Remy Cabella took the game to the Gunners, creating a wave of unconverted chances in the second half.
With a bit better finishing, Montpellier could have beaten Arsenal. But will they have the same influence—and time on the ball—in Germany on Wednesday?
Jose Mourinho has experienced a full range of emotions already this season with Real Madrid.
After league losses to Sevilla and Getafe, Cristiano Ronaldo's bouts with sadness and Real's dramatic Champions League victory over Manchester City last month, the Portuguese legend has had opportunity for anger, frustration, sadness and unbridled joy.
The joy became unbridled after Ronaldo's late winner against City last month. As Ronaldo celebrated with a slide near the end line, Mourinho stole the show with his own slide near the technical area—while wearing a snazzy-looking suit.
All that to say this: Real visit Ajax on Wednesday, and on paper Real should win the match. But it has been a wild ride for Real and Jose already this season, and some more drama—and suit slides—could be coming our way.
Match Day 1 was Isco's party, and we were all just tagging along for the ride.
The 20-year-old Spanish playmaker scored a pair of goals—the second was pure class—as Malaga outclassed Russian champs Zenit St. Petersburg 3-0 at home.
It was a memorable debut for both Isco, who's a Spain U-23 international, and Malaga, a team that had never before qualified for Europe's premier club competition.
Next up is Anderlecht—the Belgian champions—away on Wednesday, and if Isco maintains form, the results will probably be similar.
BATE Borisov and CFR Cluj pulled the upsets of Match Day 1. Now they're up against European royalty.
BATE, the reigning Belarusian champs, stormed to a 3-0 first-half lead at Lille and cruised to a 3-1 victory in the second half. Dedicated fans might remember names like Alexandr Hleb, but most will know little else about this team.
As a reward for their early excellence, BATE now face German giants Bayern Munich in Group F. Good luck with that.
Cluj, the reigning Romanian champions, stunned Braga 2-0 in both teams' Group H opener, thanks to two first-half goals from Rafael Bastos. Up next is a home game against Manchester United, a team that's still seething from a league loss at home to Tottenham over the weekend.
In all likelihood, both of our plucky underdogs have already produced their little-guy magic for the season.
But what if there's more in store?