Vinicius Junior salvaged a point for Real Madrid late on in Monday's 1-1 draw at home to Real Sociedad, though the result does little to alleviate the pressure ahead of this weekend's potentially vital derby clash with Atletico Madrid.
Zinedine Zidane's men looked to be heading towards a defeat that could have delivered a devastating psychological blow ahead of arguably their biggest game of the season, but Vinicius spared them near the end.
The hosts had the better of the first half and should have led when Mariano Diaz – again deputising for the injured Karim Benzema – inexplicably hit the frame of the goal, and La Real were emboldened by that as Portu gave them the lead with 55 minutes played.
That looked destined to be the winner and potentially the goal that ended Madrid's dwindling title hopes, yet Vinicius got them back on level terms with a minute left, albeit they still end the matchweek a further two points adrift of leaders Atletico.
Madrid somehow failed to take the lead in the 23rd minute, as Mariano nodded Lucas Vazquez's chipped cross against the crossbar from point-blank range, with Marco Asensio hammering agonisingly wide a few seconds later.
La Real goalkeeper Alex Remiro then proceeded to frustrate the hosts, first blocking a Ferland Mendy effort with his foot before parrying Luka Modric's attempt just before the interval.
The champions were made to rue their profligacy early in the second period, La Real working the ball well to Nacho Monreal on the left and his inch-perfect cross was met by a wonderful Portu header that picked out the top-far corner.
They should have made it 2-0 soon after but Alexander Isak could not reach Portu's squared pass, and Madrid subsequently wasted a glorious chance of their own – Casemiro heading off target.
Madrid did eventually restore parity as Vinicius turned in Vazquez's low cross in the dying stages. Still, they remain five points adrift of Atletico having also played a game more.