Oblak remained the busier of the two goalkeepers - tipping over a rising Ronaldo drive from 25 yards before getting down to thwart Raphael Varane following another set-piece lapse - but Keylor Navas saved excellently at his near post in the 29th minute, Koke having teed up Costa for a punt at giving Atleti the lead against the run of play.
Atletico actually had the ball in the back of the Real Madrid net in the 19th minute, but Diego Costa was adjudged to have felled Sergio Ramos in the build-up, before Oblak did well to keep out a Ronaldo strike down the other end.
"In the first half they were better, but we then started to link up better in midfield and attack".More news: Meet Qaidi No.106, Salman Khan of Jodhpur Central Jail
Atletico Madrid striker Antoine Griezmann has rubbished reports claiming a move to Barcelona is already in place but says he wants his future sorted before the World Cup in Russian Federation later this year.
Saul bent a shot narrowly wide for Atletico and Real, who brought on Luka Modric and Isco for Mateo Kovacic and Asensio, nearly snatched a late, late victor but Oblak made an excellent save from Sergio Ramos' free kick.
Atletico had a huge chance to score a second in the 82nd minute when Griezmann delivered a low cross towards Correa, but the Argentine, who was unmarked, just could not make contact.
Griezmann has nine goals in his last eight Atletico outings, so expect a few more from the Frenchman if he can continue his good goalscoring form.More news: Sinclair Broadcasting Orders Local Anchors To Record Bizarre 'Hostage' Video