Luciano Vietto's first goal for Atletico Madrid secured a 1-1 derby draw seven minutes from time and stopped Real Madrid from moving to the top of La Liga.
Karim Benzema headed his seventh goal in eight appearances this season in the ninth minute and looked to have settled a typically feisty tussle at the Vicente Calderon, where his France international team-mate Antoine Griezmann had a first-half penalty saved for the hosts.
Griezmann partly atoned for that error by having a hand in the equaliser – making enough of a nuisance of himself at the near post for Jackson Martinez's low cross to squirm beyond goalkeeper Keylor Navas for his fellow substitute Vietto to convert from close range.
Vietto's former club Villarreal lost 1-0 to Levante earlier on Sunday, presenting the opportunity for Real to take top spot.
But Rafael Benitez's team could not get over the line and lie a point off the pace in second after extending their winless run at the home of their near neighbours to six matches.
Cristiano Ronaldo headed wide early on from Luca Modric's left-wing cross but it was from the opposite flank that Real took the lead.
Dani Carvajal surged down the wing to supply an excellent cross that Benzema, who had scored just twice in 20 previous appearances against Atleti, planted emphatically past Jan Oblak.
Atleti's response was strong, with a fired-up Angel Correa to the fore.
Making his first Liga start, the midfielder collected an one-two from Oliver Torres to arrow a shot past the post from the right-hand side of the box before sending a thunderous drive wide from 30 yards.
Some ragged Real defending gifted Atleti a golden opportunity to equalise from the spot in the 20th minute – Sergio Ramos briefly looked to have retrieved the situation but took a heavy touch and clattered through Tiago.
But Griezmann's well-struck effort was at a favourable height for Navas, who sprung to his left and pushed the ball to safety.
A well-marshalled Ronaldo swivelled to shoot over after the half-hour mark, while a robust challenge on Carvajal from Oliver Torres forced Real to bring Alvaro Arbeloa on before the break.
Fernando Torres was played in by Correa five minutes into the second period but pulled an angled shot across the face of goal.
The former Liverpool striker then had an attempt blocked before making way for Jackson Martinez in the 64th minute.
A succession of fouls by both teams had badly interrupted the flow of the game by this point, with Real duo Raphael Varane and Casemiro booked either side of Juanfran to make it three yellow cards in as many minutes.
Gareth Bale followed Martinez into the Calderon cauldron, replacing Isco for his first Real action since suffering a calf injury against Shakhtar Donetsk last month.
Navas saved from Martinez in the 74th minute when Vietto found a Real body with his initial shot, while an unusually sporadic display from Ronaldo continued when he cut onto his left foot to find the side netting.
Vietto appeared crestfallen when he wasted a good headed chance in the 81st minute but the Argentine amends three minutes later – his compatriot Diego Simeone leading the boisterous celebrations from the dugout before Martinez was denied by Navas as the hosts almost snatched another famous triumph.
