A Fernando Torres double helped Atletico Madrid to a 2-2 draw at Real Madrid, giving them a 4-2 aggregate win in the Copa del Rey last 16.
Fernando Torres scored twice as Atletico Madrid progressed to the Copa del Rey quarter-finals at the expense of holders Real Madrid, drawing 2-2 on the night to prevail 4-2 on aggregate.
In the fifth Madrid derby of the season the visitors stretched their unbeaten run against their bitter rivals, who they last lost to in the 2014 UEFA Champions League final.
Diego Simeone's side had won three of the four previous clashes against Real this season - including their 2-0 first-leg success at Vicente Calderon last week.
That put the onus on Real to attack in Thursday's return fixture at the Santiago Bernabeu and they were hit twice on the counter by Torres, who scored his first Atletico goals since returning on loan from Milan last month.
The 30-year-old forward, who started his career at Atletico, put the visitors in front after just 50 seconds, setting Carlo Ancelotti's side an even bigger task.
Simeone said before the match he expected a Real onslaught and it duly followed, as the European champions produced wave after wave of first-half attacks.
They had only Sergio Ramos' header to show for it, though, and Torres' second - scored inside the first minute of the second half - virtually killed off the tie.
There was still time for newly crowned FIFA Ballon d'Or winner Cristiano Ronaldo to net a header, but ultimately it counted for little as Atletico - last season's Liga champions - retained the bragging rights in the Spanish capital.
Torres replaced the ill Mario Mandzukic while the likes of Gabi and Arda Turan dropped to the bench for Atletico.
And the ex-Liverpool and Chelsea striker fired the visitors in front in the first minute after Antoine Griezmann stormed past Pepe and down the left.
Griezmann's cross was inch-perfect and a free Torres turned back the clock with an excellent finish, curling past Keylor Navas with aplomb.
The goal stunned Real into action and, predictably, they dominated thereafter, but the sheer weight of numbers in Atletico's defence made life tough for Ancelotti's men.
Pepe and Gareth Bale failed to convert headers but Ramos had no such problems in the 20th minute, although he was undoubtedly helped by Jan Oblak's poor decision to come for Toni Kroos' free-kick.
That allowed Ramos a sight on goal and he rose highest to nod in the set-piece, bringing the home crowd to life.
Ronaldo should have cut the aggregate margin to one in the 24th minute after Oblak again came off his line and failed to collect, but Diego Godin produced a crucial block and, as the half went on, Real were reduced to a series of unsuccessful crosses in a bid to break Atletico's stubborn resolve.
The hosts were then hit with the ultimate sucker-punch as Ramos' poor ball out of defence paved the way for Torres' second.
Ramos could only find Griezmann with his attempted pass and, just as with the first goal, the Frenchman stormed forward and caused problems with his trademark pace.
He then fed Torres, who took a touch to create space, before the striker fired in - via the trailing leg of Navas.
Griezmann shot just wide in the aftermath but Ronaldo levelled on the night in the 54th minute, powerfully heading in a Bale cross.
Turan replaced Torres as the away side looked to make life even tougher for Real, who were frustrated when Karim Benzema volleyed over from a corner.
Pepe was forced off with a chest injury but Ancelotti turned down the chance to bring on an attacking player in his place as the match petered out.
And although Bale had a half-chance late on, the night belonged to Torres and Atletico, who are likely to face Barcelona in the last eight.