On Sunday, the German leaders Bayern Munich, Real Madrid and PSG lost to Spain's leaders.
It is not very often that Barcelona, Real Madrid and Paris St-Germain lose a league match. Even rarer is it for two or three of these giants to be defeated in the same weekend. It is very unlikely that all four of these giants will lose on the same weekend.
This is exactly what happened in Europe's top divisions on Saturday, and Sunday. All four clubs had unbeaten seasons.
Barcelona's defeat to Atletico Madrid, champions of the tournament, was not surprising considering the Catalans' current state of affairs. However, the other three upsets were significant.
Ajax, the Dutch champions, also lost in the Eredivisie - their first loss of the campaign. This is the first time Bayern, Real, and Ajax have all lost a league match together.
Here's what happened from Bayern's home run to Lionel Messi losing his first game in France.
Bayern Munich 1-2 Eintracht Frankfurt
Bundesliga leaders Bayern Munich lost a home match for the first-time since November 2019, when Eintracht Frankfurt won a late victory at the Allianz Arena.
Julian Nagelsmann's team, who are currently top in goal difference, led Leon Goretzka's opener, but Filip Kostic scored the winner with seven minutes left after captain Martin Hinteregger had equalised.
This was Frankfurt's first away win at Bayern since November 2000, and ended the hosts' 30-match unbeaten streak.
Nagelsmann stated that defeats always hurt. "Today, that was also the case. It was our first loss and it was entirely avoidable.
Espanyol 2-1 Real Madrid
Five days after suffering a humiliating Champions League defeat at Sheriff Tiraspol's Bernabeu, Carlo Ancelotti would have expected strong responses from Real Madrid players.
Espanyol, against whom they had only lost one of their previous 25 league meetings, defeated the visitors and ended their 25-match unbeaten streak in La Liga.
The leaders suffered successive defeats due to goals from Raul de Tomas, a former Real player, and Aleix Vidal's amazing solo finish. They failed to contribute to Karim Benzema’s lifeline.
Ancelotti acknowledged that Real had played their worst match of the season. He said: "I agree, it was a bad match. The international break is a good opportunity to reflect on why the team's attitude changed within a week.
Rennes 2-0 Paris St-Germain
PSG made a great start to their quest for the Ligue 1 title. They took maximum points from eight of their first eight Lleague games. A win at Rennes would have put them nine points ahead at the summit.
The hosts shocked Mauricio Pochettino as Gatetan Laborde scored just before the half-time break and Flavien Tait added a second shortly after the restart, resulting in PSG's first league loss since April. Despite Neymar, Lionel Messi and Kylian Mbappe starting, the Parisians failed to score a single goal.
This was their first loss since Messi's arrival in the summer. They are still six points ahead at the top, so there is no need to panic.
Pochettino said, "I'm really disappointed by everything." "I believe we now need those two weeks, but the players will be on international duty. It's now time to start thinking and to plan the next six games over the coming months.
Ajax 0-1 Utrecht
After storming to the title last year, Ajax won six of their seven Eredivisie matches. They finished with a 16 point lead.
Utrecht is a hot favorite for the October international break, after the surprise of the Johan Cruyff arena visitors.
Django Warmerdam, left-back, scored the only goal in the final minute to win all three points. This was despite Ajax dominating the game with 69% possession (and 20 shots to the visitors) Ah, football.
Erik ten Hag, manager, said that "we weren't 'on' the first minute." That means that you must have 100% focus and pace. This was not possible."
Atletico Madrid 2-0 Barcelona
Although we don't think you can call this an upset given the current state of Barcelona, 26-time La Liga winners were handed a humiliating defeat by Atletico Madrid, reigning champions.
Barca was not hurt by the loss, but the way it was done. Atletico cruised to a comfortable win at Wanda Metropolitano with a comfortable 2-0.
Ex-Barcelona striker Luis Suarez scored Atletico's second goal after Thomas Lemar had put them in front.
This was Barca's first league loss of the season. However, it comes on the heels of their second consecutive 3-0 loss to Benfica in the Champions League.
Joan Laporta, the club president, gave Ronald Koeman a vote to confidence before Saturday's match. She said that Clarity was very important for both the coach and the players. Barca is still Barca. We must win more games. This pressure is normal.
It exists for all coaches, and even more at Barca. But the president has spoken well. He has made his decision as he stated this afternoon and everything is perfect.
If you say so, Ronald.