Real Madrid completed a miserable week when they slipped to a third defeat in a row after losing 1-0 at Espanyol in the Spanish Primera Liga on Sunday.
Champions Barcelona also suffered as they were dealt their first loss of the season when they went down 2-1 at Atletico Madrid in the day's late match.
A determined and well-organised Espanyol grabbed victory when defender Daniel Jarque got behind the Real back four to head in Ivan de la Pena's free kick 22 minutes from time.
Real's pride was further wounded when two of their new signings sent off in the closing minutes.
Sergio Ramos was dismissed for a body check on the outstanding De la Pena as he surged towards goal and Julio Baptista followed him down the tunnel in injury time after a reckless studs-up challenge on substitute Jonathan Soriano.
Real lost 3-2 to Celta Vigo at the Bernabeu last Saturday before being put to the sword in a 3-0 defeat at Olympique Lyon in the Champions League on Tuesday.
The results are a carbon copy of the events that led former coach Jose Antonio Camacho to throw in the towel last season when Real lost 3-0 to Bayer Leverkusen in Europe and 1-0 at Espanyol in their third league game with two players sent off.
Barca took an early lead when Samuel Eto'o steered in from close range but Atletico hit back with their first goal of the season when Fernando Torres powered in a header after Bulgarian winger Martin Petrov had torn his way down the left flank.
Mateja Kezman scored the winner when he ghosted in at the far post early in the second half and Atletico withstood some heavy pressure after being reduced to 10 men when centre back Pablo Ibanez was sent off with 23 minutes still to play.
PULSATING WIN
Earlier, Bernd Schuster's Getafe claimed top spot in the Primera Liga for the first time in their history thanks to a pulsating 4-3 win at Alaves.
The modest Madrid-based side, who played in the top flight for the first time last season, twice came from behind to goals from Alaves's Brazilian striker Nene in the opening half hour.
Striker Riki put Getafe ahead with his second goal when he volleyed home seven minutes from the break and defender Mariano Pernia made it 4-2 early in the second half with a curled free kick into the top corner.
Nene notched his hat-trick with a second penalty in the 65th minute but it was still not enough to prevent a defeat.
Getafe join Deportivo Coruna, who drew 2-2 at Valencia on Saturday, at the top on seven points, one ahead of Celta, who dropped their first points this season in a 1-0 defeat at home to Racing Santander.
Real Madrid had the better of the early play at Montjuic and Ronaldo almost gave the visitors the lead when he powered a close-range header against the base of the post after David Beckham swept a free kick into the area.
But they began to run short of ideas as the half wore on and it was Espanyol who appeared to have a much clearer game plan with their deep defending and swift counter-attacks.
The Catalans finally broke the deadlock when Jarque headed in De la Pena's probing free kick, although Real complained they heard the referee's whistle just before the goal was scored.
Real then lost their cool completely in the final minutes with Ramos and Baptista deserving their marching orders.
The defeat left Real in 15th place with three points from three matches. Barcelona are eighth just a point ahead of Real.