After a cautious opening from both sides and a period in which Real Madrid had 72% possession, the game exploded into life around the 15-minute mark as a series of combative exchanges involving Vinicius Junior, amongst others, riled the home support.
Ante Budimir had Osasuna’s first shot at goal shortly after, and he was only a whisker away with a curled effort that had Thibaut Courtois beaten.
The Belgian then pulled off a world-class one-handed save after a whipped ball into the box caused confusion, and Budimir hit the post with a header from just inside the area.
Vinicius’ trickery, Kylian Mbappe’s long-range daisy cutter and David Alaba’s rocket from distance might all have given Los Blancos the advantage on another day, but after Courtois was adjudged to have fouled Budimir in the area, the Croatian stepped up from the spot to put the hosts 1-0 up with a simple left-footed finish.
Both sides spent much of the first 10 minutes of the second half trading blows without a hint of a goal, until Arda Guler flashed over a right-footed exocet that had Sergio Herrera floundering.
Osasuna’s energy and ability to move the ball around with ease eventually resulted in a double substitution from their visitors, and one of them, Trent Alexander-Arnold, almost immediately injected the pace and purpose that had been missing from Real’s play.
Mbappe smashed a beautiful effort into the top corner, only to see the offside flag raised, though it was another sign that Los Blancos were slowly but surely easing themselves back into the game.
Immediately, a stunning run and cross from Federico Valverde set up Vinícius, who couldn’t miss from six yards out, and only Javi Galan’s last-ditch block stopped Mbappe from adding a quickfire second.
In the final minute, an astonishing individual finish from Raul García won the match for the hosts.
The late goal also ended Real Madrid's 24-game unbeaten run in H2Hs against Los Rojillos (D7, W18), which had dated back to January 2011. More importantly, the defeat offers Barcelona an opportunity to usurp Los Blancos when the Blaugrana face Levante on Sunday.
Flashscore Man of the Match: Valentin Rosier (Osasuna)