Juventus's perfect start to the season came to a halt when they were beaten 3-1 by AC Milan at the weekend but Chelsea, Bayern Munich and Olympique Lyon continued dominating their respective leagues.
Ronaldinho inspired Barcelona to a 5-0 win over Real Sociedad as the Catalans moved to within two points of Primera Liga leaders Osasuna, while Rosenborg Trondheim's 13-year stranglehold on the Norwegian title was broken by Valerenga.
First-half goals from AC Milan's Clarence Seedorf, Kaka and Andrea Pirlo at the San Siro ended Juventus's nine-match winning start to the season.
France striker David Trezeguet pulled a goal back for Juventus in the 76th minute but it was not enough to stop Milan moving within two points of the champions.
Chelsea, who lost their 100 percent record at Everton last weekend and were knocked out of the League Cup by Charlton Athletic in midweek, returned to winning ways with a 4-2 triumph at home to Blackburn Rovers.
Neither of the clubs expected to challenge the English champions this season could manage a win, with Arsenal needing a Robert Pires equaliser to draw 1-1 at Tottenham Hotspur in the north London derby and Manchester United humbled at Middlesbrough.
Spaniard Gaizka Mendieta scored twice as United went down 4-1 in what coach Alex Ferguson described as a "shocking performance".
Promoted Wigan Athletic, who beat Fulham 1-0, are second, nine points behind Chelsea.
French champions Lyon, who also lost on penalties in the League Cup in midweek, opened up a similar size gap over Girondins Bordeaux at the top of Ligue 1 after Florent Malouda scored the only goal of their game against Sochaux.
Germany captain Michael Ballack once again showed his value to Bayern Munich, a headed goal 16 minutes from time sealing a 2-1 win at Cologne and keeping the champions two points clear at the top of the Bundesliga.
Werder Bremen stayed within striking distance after coming from behind to beat Eintracht Frankfurt 4-1.
Third-placed Hamburg SV ended Schalke 04's unbeaten start to the season, Mehdi Mahdavikia getting the only goal of the game.
As if stung into action by Chelsea manager Jose Mourinho's description of his midfielder Frank Lampard as the best player in the world, Brazilian Ronaldinho was on top form in the drubbing of Real Sociedad at the Nou Camp on Sunday.
The FIFA and FIFPro world player of the year scored twice after setting up Dutchman Mark van Bommel for the opening goal as the Spanish champions closed in on surprise early leaders Osasuna, who stayed top with a 2-0 win over Espanyol.
Third-placed Real Madrid beat Real Betis 2-0 on Saturday, goals from Robinho and Alvaro Mejia bringing an end to their two-match losing streak in the league.
Celtic restored Glasgow's pre-eminence in Scotland by taking advantage of the 2-0 defeat of league leaders Hearts at the hands of Edinburgh rivals Hibernian. A 4-2 win at Dundee United was enough to put Celtic top for the first time this season on goal difference. Champions Rangers could only manage a 1-1 draw with Inverness Caledonian Thistle and are fourth, 10 points behind the top two.
Dutch champions PSV Eindhoven retained their one-point lead at the top of the first division with a 1-0 win over Twente Enschede on Saturday.
AZ Alkmaar won 2-0 at ADO Den Haag to remain second, equal on points but with a better goal difference than third place Feyenoord, 3-1 winners at Willem II Tilburg on Sunday.
It may be early season in the more temperate parts of Europe but in Scandinavia it is the business end of the campaign.
Valerenga won the Norwegian championship on Saturday after their 2-2 draw at Odd Grenland, becoming the first club apart from Rosenborg to win the title since 1991.
It was Valerenga's fifth title, their first since 1984, and they needed the point to pip promoted IK Start, who were favourites going into the last round of matches but lost 3-1 to visiting Fredrikstad. Rosenborg finished seventh.In Sweden, Djurgarden clinched the double on Saturday by beating second division Atvidaberg 2-0 in the Swedish Cup final.