And when Cristiano Ronaldo finally beat him in the first half, defender Stefan Savic hustled back to clear his goal-bound strike with his head.
Pepe put Real ahead in the 52nd, when he shook off his marker and headed Toni Kroos' free kick just inside the far upright.
Manchester City and Chelsea have made contact over Antoine Griezmann's situation at Atletico Madrid.
Atletico Madrid president Enrique Cerezo has categorically denied reports that Real Madrid could buy Theo Hernandez, saying "people should be more serious".
Saul Niguez had the first chance, heading Koke's free-kick inches wide, before Yannick Carrasco crossed for Griezmann, who hit the post only to be ruled offside.
Oblak was beaten on the half-hour mark but Savic came to Atletico's rescue, the centre-back heading Ronaldo's strike from close range up and over the crossbar from nearly on the goal line. Griezmann did the rest, slotting his shot past Keylor Navas for his third goal against Real in Atletico's red-and-white.
But Oblak could do nothing to stop Madrid taking the lead on 52 minutes through an unlikely source.
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This week, the White House announced that Bannon had been removed from the National Security Council by President Donald Trump . Gary Cohn, the president's economic adviser and former No. 2 at Goldman Sachs, is on the list as well, according to the site.
"We played a great game against a great rival, but we dropped our guard for one moment", Real midfielder Casemiro said.
Pepe gave Zidane some cause for concern 23 minutes from time when he was forced off following a collision with Kroos on the edge of the area, while Simeone threw on Angel Correa in an effort to breathe life into Atleti's attack.
That was until Correa, who had gone on in the 61st, saw the sliver of space between Real defenders Nacho Fernando and Dani Carvajal.
- Real Madrid have scored more goals from set-piece situations than any other side in La Liga this season (25).
With nine minutes to go, Bale was substituted for Lucas Vazquez as the home side looked to change things in their frontline.
Scans revealed he would miss both legs against Bayern, who warmed up for Wednesday's showdown with a 4-1 thumping of Borussia Dortmund.