How do Europe's top 10 clubs stack up at quarter mark of the season?

Coming out of the October international break - the unofficial quarter point of the European football season - we're taking stock of the 10 clubs we believe are the best on the continent right now. Can anyone challenge the Champions League holders?

Note: Expected goals for (xG) and against (xGA) are courtesy of Football Reference; an explainer on the metric can be found here.

1. Liverpool

1st in Premier League

Aside from the odd wobble - a loss to Napoli in the Champions League, for instance - it's hard to argue with Liverpool, who emerge from the opening two months of the season with an unblemished league record. It's all the more impressive considering Alisson - who's equally vital both as a traditional shot-stopper and, more famously, as a ball distributor - has played less than 45 minutes thus far. The Brazilian's impending return makes the Reds markedly better - a frightening proposition for the chasing pack below.

2. Bayern Munich

3rd in Bundesliga

Mired in the quagmire that is the Bundesliga table, Bayern Munich haven't truly put their foot on the gas just yet. Their 7-2 demolition of Tottenham in the Champions League, though, is the standout result of the season thus far. While it says plenty about the crumbling side Mauricio Pochettino is trying to hold together with duct tape, we shouldn't lose sight of the fact that Bayern are scary good. Robert Lewandowski is on fire, Kingsley Coman and Serge Gnabry have been lethal, and Philippe Coutinho is offering an added spark after being freed of his Barcelona shackles.

3. Manchester City

2nd in Premier League

It turns out having more than one reliable central defender in your squad is a good idea. Who knew? The decision not to invest in that area this summer was always puzzling, and stud center-back Aymeric Laporte's injury has crippled Manchester City's backline so far. They're still dazzling in attack, obviously - Raheem Sterling is in the midst of an enormous statistical year - but City are conceding big chances with worrying regularity, as evidenced by their home defeat to Wolverhampton prior to the international break. There's too much raw talent for them not to be a threat, but as long as Nicolas Otamendi is playing meaningful minutes, questions remain.

4. Paris Saint-Germain

1st in Ligue 1

Instead of going for overly lavish signings this summer, Paris Saint-Germain's (relatively) thrifty approach in the transfer market has paid off handsomely, creating a more nuanced, balanced side that can withstand key absences. PSG are obviously better with the oft-injured Neymar in the lineup - don't believe anyone who tells you otherwise - but Thomas Tuchel has so many attacking options at his disposal that he'll be able to withstand the Brazilian's latest ailment. Just ask Real Madrid.

5. Juventus

1st in Serie A

It took some time, but if the assertive win over title rivals Inter was any indication, Maurizio Sarri's tactical imprint is starting to shine through at Juventus - the 24-pass sequence that led to Gonzalo Higuain's winning goal was a perfect testament to that. Elsewhere, Juan Cuadrado has been surprisingly solid at right-back, solving what seemed to be a huge preseason issue for the Bianconeri. As the likes of Douglas Costa and Aaron Ramsey return to fitness, and Adrien Rabiot and Matthijs de Ligt get more comfortable, there's only one direction this team can go.

6. Barcelona

2nd in La Liga

Barcelona have looked like a complete mess on multiple occasions this season, with under-fire boss Ernesto Valverde thus far unable to figure out the best way to utilize Luis Suarez and Antoine Griezmann together. Sergio Busquets looks increasingly washed, while standout 'keeper Marc-Andre ter Stegen has been forced to bail his teammates out far too many times. But as long as Lionel Messi is around, Barca will be among Europe's best teams. It's that simple, really.

7. Real Madrid

1st in La Liga

Flipping the script that we've grown so accustomed to in recent years, Zinedine Zidane's Real Madrid have been a formidable force in La Liga, only to fall flat on their faces in the Champions League. What a world. They'll likely still reach the knockout stages, but a blowout loss to PSG and a humbling home draw against Club Brugge highlighted some alarming issues for a squad that, while spectacular on paper, has plenty of kinks to iron out.

8. Atletico Madrid

3rd in La Liga

Scoring few and conceding even fewer; some of the old guard have moved on, but this remains a Diego Simeone side through and through. And that might be the problem. Still one of the best teams in Europe - hence their appearance here - Atletico Madrid have a legitimately impressive crop of forwards, highlighted by rising Portuguese superstar Joao Felix. Can Simeone figure out a way to unleash the attacking potential of his squad without compromising that vaunted defensive solidity?

9. Inter Milan

2nd in Serie A

Antonio Conte has come in and immediately reinvigorated Inter Milan in much the same way he did with Juventus, Italy, and Chelsea before them. Losing Alexis Sanchez for three months due to an ankle injury suffered during the international break is a blow - the Chilean's Inter career had actually gotten off to a promising start - but there's adequate depth to withstand his absence. The meek setback against Juve notwithstanding, Inter's performances so far suggest they'll take the Serie A title race down to the wire.

10. Borussia Dortmund

8th in Bundesliga

We're going to learn a lot about this Jekyll and Hyde club in the coming weeks. Borussia Dortmund's next seven matches in all competitions read like the ultimate gauntlet. Meetings with the top three sides in the Bundesliga - Monchengladbach, Wolfsburg, and Bayern Munich - sandwich a derby tilt against Schalke - sprinkle in two massive Champions League clashes with Inter and a DFB-Pokal date with Gladbach for good measure. Are BVB a legitimate top 10 team, or was last season's title push an aberration?

Honorable mentions: RB Leipzig, Napoli