Sergio Ramos was sent off for a record 19th time in La Liga as Real Madrid drew 0-0 Athletic Bilbao and failed to take advantage of Barcelona's earlier slip.
Real remain eight points behind Barcelona, who were held 2-2 by Celta Vigo at the Camp Nou earlier in the day.
Karim Benzema and Cristiano Ronaldo both hit the woodwork but Bilbao stood firm to the delight of the San Mames crowd.
As frustration continued to grow in Real ranks, skipper Ramos -- who was cautioned in the first half -- was sent off four minutes from time for a rash challenge on Aritz Aduriz.
It was the 24th time in all competitions that Ramos has seen a red card in his career.
Real named the same side that had beaten Juventus in the Champions League final in June.
But Real's sparkle has faded since that memorable night in Cardiff and Ronaldo and company were unable to break down stubborn Bilbao hosts.
Real carried the greater attacking threat in the first half and the home defence was almost unlocked in the eighth minute.
Isco's cross from the left just cleared the head of Ronaldo but Benzema took the ball on his chest and struck the post from 12 yards.
Bilbao's response saw Aduriz connect with an Oscar de Marcos cross which forced a full-length save from Keylor Navas.
Ronaldo appeared determined to improve a record which has seen him only score two goals in LaLiga this season.
But Ronaldo cut a frustrated figure as he fired a free-kick wide before sending a 20-yard shot straight at Kepa Arrizabalaga in the home goal.
Arrizabalaga also saved routinely from Toni Kroos before Navas was stretched at the other end after 28 minutes.
Raul Garcia played a clever ball into Inaki Williams's path and his effort was destined for the bottom corner until Navas intervened.
There was an even clearer chance for Bilbao moments later when Mikael Susaeta flighted a free kick towards Garcia at the far post.
Garcia turned it back across the six-yard box, but Aduriz could not get the cleanest of connections and sent the ball wide.
Real went close when Kroos shaved the post from 18 yards before Ronaldo dragged his volley wide with the Bilbao defence stretched.
The visitors had dominated possession and territory in the first period but they had a scare three minutes after the restart.
Susaeta intelligently cut the ball back to Aduriz but his well-struck shot was pushed away by Navas.
The Costa Rican had to be alert again when Susaeta tried to loft the ball over him near the byline.
Real were lacking penetration around the Bilbao box but, with 20 minutes remaining, Isco chipped the ball up to Ronaldo.
The Portuguese's volley from 18 yards clipped the base of the post and Real's pressure continued to grow.
Arrizabalaga batted away Marcelo's ferocious angled drive and Bilbao's goal was leading an increasingly charmed life.
But the departure of Ramos saw the balance of power shift and Bilbao looked the more likely winners in the final moments.