You wait weeks for one of Europe's top sides to lose and make things interesting, then loads of them go and do so on the same weekend. Football is a funny beast sometimes.
Sevilla, Arsenal, Napoli, Chelsea, Atletico Madrid, Bayern Munich, Paris Saint-Germain, Juventus and Manchester City all fell to defeat over the past seven days, making for some rather difficult decisions with regard to who should be placed where in our European Club Rankings.
You can read the previous set of rankings here.
20. Lille (New!)
Entering the rankings for the first time ever are Lille, who continue to win Ligue 1 games in impressive fashion. Their 46-point haul from 23 games is a brilliant return, and it's got a lot to do with the incredible form of Nicolas Pepe, who has 16 goals and eight assists already.
19. Sevilla (-5)
Sevilla are in a slump. They've lost five of their last seven in all competitions, leaking goals at a worrying rate, and they plummet down our rankings as a result.
18. Borussia Monchengladbach (+1)
Gladbach chalked up yet another win this weekend, beating Schalke 04 away from home thanks to late goals from Christoph Kramer and Florian Neuhaus. It takes them up to second in the league, ahead of Bayern Munich.
17. Arsenal (Stay)
Sometimes a week in football can be very revealing. Sometimes it can teach you nothing at all.
Arsenal's past week falls into the latter category. Predictably they beat Cardiff City at home in midweek, and predictably they lost at the Etihad Stadium to Manchester City.
The Gunners' wait for an away win against a top-six Premier League side goes on (the last was in January 2015).
16. Lyon (+2)
Lyon played the role of party-poopers on Sunday night, handing Paris Saint-Germain their first Ligue 1 loss of the season thanks to an awesome display at the Groupama Stadium.
Goals from Moussa Dembele and Nabil Fekir, plus an incredible goal-line headed clearance from Jason Denayer, paved the path to victory.
15. Real Madrid (+1)
Two hallmarks of a much-improved January for Los Blancos have been Karim Benzema goals and Vinicius Junior starts. Both came through for the club against Deportivo Alaves, netting one each as they coasted to a third straight La Liga win.
14. Ajax (+1)
Vengeance? Ajax responded to two disappointing Eredivisie results with a 6-0 thrashing of helpless VVV-Venlo. Big performances from Hakim Ziyech, Dusan Tadic, David Neres and Donny van de Beek ensured De Godenzonen got back on track.
13. FC Porto (Stay)
Porto bounced back from their cup final loss last week with a comfortable 3-0 victory over Belenenses. It was the Primeira Liga leaders' 11th clean sheet of the season from 19 games.
12. Napoli (-1)
It was a mixed week for Napoli. Midweek saw them lose 2-0 to AC Milan and drop out of the Coppa Italia—a crying shame, given Juventus also bowed out—but this weekend saw them beat Sampdoria 3-0 in a strong display.
Despite the performance, the headlines focused almost solely on Samp's Fabio Quagliarella. The Naples-born striker had the chance to break the Serie A record for goals in consecutive matches (12) against his hometown club but couldn't; he remains level with Gabriel Batistuta on 11.
11. Chelsea (-1)
How do you gauge a week like the one Chelsea had?
A 4-0 loss to Bournemouth was followed by a 5-0 win over Huddersfield Town. It's tempting to say they broke even, but considering how poor the latter opponents are, that's probably not even the case.
At the very least, Eden Hazard sparked back into life and Gonzalo Higuain got off the mark for the Blues. Those represent building blocks Maurizio Sarri is badly in need of.
10. Tottenham Hotspur (+1)
Two late, late shows from Tottenham last week secured six Premier League points, steadying their situation somewhat.
Heung-Min Son scored against both Watford and Newcastle United to make the difference, though some credit must go to Fernando Llorente. He's got his critics and has missed some chances, but he also had a big hand in both results.
9. Manchester United (Stay)
It proved to be the most difficult week of Ole Gunnar Solskjaer's reign at Manchester United so far, as the Red Devils had to rescue a point at home late to Burnley on Tuesday before sneaking past Leicester City on Sunday.
For the first time under the Norwegian, it seemed United lost a bit of steam. Against Leicester, they were pretty fortunate not to concede, relying on last-ditch defensive actions too often for comfort.
Results are results, though, and this team continue their excellent vein of form.
8. Atletico Madrid (Stay)
A dream debut for Alvaro Morata didn't materialise. His first match for Atletico Madrid ended in defeat to Real Betis, with his new club managing just a single shot on target and relying on goalkeeper Jan Oblak to keep the deficit down.
It's not the return Diego Simeone would have expected from such an attacking XI.
7. Bayern Munich (Stay)
The five-match win streak—and the progress attached to it—has come to a screeching halt. A poor performance from Bayern Munich on Saturday saw them lose 3-1 to Bayer Leverkusen.
It opened up all the discussions fans were having before Christmas: Why can't this team play for 90 minutes? Why doesn't Niko Kovac have a Plan B when things aren't working? As soon as the winning stops, the questioning starts again.
6. Paris Saint-Germain (Stay)
There will be no unbeaten Ligue 1 season for PSG in 2018-19. Lyon made sure of that on Sunday night, beating the capital club 2-1 in a tense encounter.
After falling behind in the second half, Thomas Tuchel made the quizzical decision to remove Edinson Cavani from the fray. As his charges poured forward in the most incoherent of ways, it was actually Lyon who came closest to adding to their tally.
It's hardly the sort of performance you want to be dropping leading up to a tussle with an inspired Manchester United side.
5. Juventus (-4)
Juventus' past week resembled something approaching a nightmare. It brought their first winless streak (they failed to win two games in a row), and they were comprehensively dumped out of the Coppa Italia.
Atalanta struck the most meaningful blow in midweek, beating the Bianconeri 3-0 at the quarter-final stage. It's a competition Juve have become used to winning, lifting the trophy for the last four years in a row, and it's not even as if they fielded an understrength side—Cristiano Ronaldo, Paulo Dybala and Co. all started.
A retort was expected at home to Parma on Saturday, but instead they conceded a 92nd-minute equaliser to Gervinho, dropping points in Serie A for the first time this year.
Have Juventus gone soft on the eve of the Champions League knockout stages?
4. Manchester City (Stay)
The nature of Manchester City's midweek loss to Newcastle United blew a lot of minds.
They went from taking the lead incredibly early and applying a lot of pressure to completely relaxing and allowing their opponents back into the game. Salomon Rondon and Matt Ritchie made them pay for it.
It looked like they were set to do the same against Arsenal on Sunday, scoring early again and then taking their foot off the gas, but City snapped out of their malaise and saw it out.
3. Liverpool (Stay)
It's possible to view Liverpool's midweek result two ways, depending on your persuasion.
The positive spin is that the draw against Leicester City temporarily took them five points clear at the top of the table. The negative spin is that, for the first time this season, the Reds dropped points to a team outside of the top six—and at home—on a night when they could have pulled seven clear.
Was it merely a wobble, or is the pressure getting to them? We can't know at this stage, but Monday's game at West Ham United could serve as another major hint.
2. Barcelona (+3)
Barcelona took part in one of the most entertaining games in some time last week, roaring from 2-0 down on aggregate in the Copa del Rey to win 6-1 (6-3 overall) against Sevilla.
Perhaps the effort and emotion expended that night led to the sloppy start against Valencia on Saturday—Lionel Messi netted a brace to save a point after the hosts went 2-0 down inside the first 32 minutes.
The second-half onslaught in search of a winner was quite the sight, forcing some heroic defensive actions, but it also led to a series of counter-attacks Los Che really should have buried.
Barcelona are very good, but they are just as imperfect as they've always felt under Ernesto Valverde.
1. Borussia Dortmund (+1)
Sometimes it just seems certain things will happen, like they're written in the stars. Borussia Dortmund winning the Bundesliga this season is one of those things.
On the weekend when they finally dropped points, securing only a draw in a tricky fixture at Eintracht Frankfurt, they actually moved further clear of Bayern Munich in the table after the Bavarians lost.
They also move up in the European Club Rankings, claiming the top spot. That's as much to do with Juventus' rough week as it is anything else.
All statistics via WhoScored.com.