Atletico Madrid are through to the quarter-finals of the Copa del Rey after an Antoine Griezmann double inspired them to a 3-0 win over Rayo Vallecano and a 4-1 aggregate success.
Diego Simeone's La Liga leaders went into Thursday's second leg at the Vicente Calderon with a slight advantage on away goals having drawn 1-1 at Vallecas in the first leg.
But Atletico - hit with a transfer ban for the next two windows by FIFA earlier in the day - were made to work hard by their neighbours, who produced a battling performance that belied a league position of second bottom in Spain's top flight.
Indeed, chances proved few and far between as both teams struggled to take advantage of attacking openings.
But Angel Correa broke the deadlock with a moment of inspiration, the 20-year-old forward finding the net in the 40th minute with a powerful effort that left Rayo goalkeeper Yoel with no chance.
Atletico laboured in their attempts to put the game and tie beyond doubt but did so 10 minutes from time thanks to Griezmann, who then pounced on a goalkeeping error to score his second of the game in injury time.
Rayo started positively and Adrian Embarba tested Atletico goalkeeper Miguel Angel Moya in the 13th minute with a low shot on the turn from the edge of the area.
Despite enjoying long periods of possession, Atletico struggled to create clear-cut opportunities, although midfielder Thomas Partey drew a fingertip save from Yoel with a fine header from a left-wing free-kick just after the half-hour mark.
But Correa did open the scoring five minutes before half-time in stunning fashion.
The Argentina international met Yannick Ferreira Carrasco's lay-off with a fearsome right-footed strike from just inside the 18-yard box that cannoned in off the inside of the crossbar.
Correa was then sent through on goal by an excellent lofted pass from Jesus Gamez, but Rayo defender Quini recovered superbly to divert his square pass for Jackson Martinez behind for a corner.
Embarba flashed an effort wide as Rayo sought to send the tie to extra-time before Atletico striker Martinez was denied by a one-on-one save from Yoel, with Ze Castro preventing Griezmann from converting the rebound.
But from the resulting corner Griezmann ensured Atletico's progress, bundling the ball in at the second attempt from Stefan Savic's near-post flick-on.
And Griezmann sealed a comfortable win in stoppage time, when he nicked the ball beyond Yoel and placed it into the empty net for his 16th goal of the season.