Real Madrid's King's Cup exit to Atletico on Thursday was more evidence Diego Simeone's side have the measure of the European champions this season and left Real coach Carlo Ancelotti scratching his head for a solution.
A resurgent Fernando Torres struck twice in a 2-2 draw with the holders at the Bernabeu that sent Atletico through 4-2 on aggregate and set up a clash against record winners Barcelona in this month's quarterfinals.
The Torres goals, his first against Real at their giant arena in the Spanish capital, came in the first minute of each half following the kind of defensive errors Real rarely commit.
First, Pepe let Antoine Griezmann skip past him with a badly-timed lunge and then a wayward Sergio Ramos pass gifted possession to the France forward in central midfield.
Real have played five matches against Atletico this season, losing 2-1 on aggregate in the Spanish Super Cup and 2-1 at the Bernabeu in La Liga.
Ancelotti said he was still searching for a way to get the better of Simeone this term, in contrast to last season when Real knocked Atletico out of the Cup and beat them in the Champions League final.
"The key to the match was the two mistakes and that is something we have to correct," Ancelotti told a news conference.
"We found the right formula (against Atletico) last season but not yet this one," added the Italian.
"We know that they are a very strong team and we will try to plan the next game against them in the best way possible."
Real's next outing is a La Liga game at Getafe on Sunday, when they will be seeking to protect their one-point lead over second-placed Barca with a game in hand.
Atletico, who host Real in La Liga at the Calderon next month, are three points behind Barca in third after Sunday's 3-1 defeat at the Nou Camp.
Real are also through to the last 16 of the Champions League, the competition they won for a record-extending 10th time last season, and will play Schalke 04.
They could meet Atletico, who were drawn against Schalke's Bundesliga rivals Bayer Leverkusen, in April's quarterfinals.
"We made mistakes that we don't usually make and we had problems bringing the ball out of our own half," Ancelotti said.
"It's the first time this has happened and I don't think it will happen again."
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