Karim Benzema missed a penalty for Real Madrid as they finally blinked in the La Liga title race, dropping their first points of the season in a 1-1 draw with Osasuna on Sunday.
Elsewhere, Real Sociedad won 5-3 at Girona, and high-flying Real Betis fell to a 1-0 defeat at Celta Vigo.
After Barcelona beat Real Mallorca on Saturday, Madrid knew they had to win to stay top but were frustrated by Jagoba Arrasate's well-organized side at the Santiago Bernabeu.
Benzema, on his return to the side after injury, won a spot-kick but then fired it against the crossbar and also had a goal disallowed for offside as Madrid tried to force a way through.
Vinicius Junior broke the deadlock just before halftime with a cross that snuck all the way into the far corner, but Kike Garcia's well-taken header early in the second period earned Osasuna a point.
"What we were missing was scoring that penalty; normally, Karim scores them," Madrid coach Carlo Ancelotti told DAZN.
"He had no problem playing the 90 minutes. It's been a month since he's played; he has to get his best form back. He did his part; he had the chance from the penalty. It's an accident; sometimes it happens."
Real Madrid president Florentino Perez told the club's fans at an assembly on Sunday morning that a European Super League project was essential, but Osasuna showed domestic football can still offer a significant challenge.
The draw means Barcelona lead Madrid on goal difference after seven games, with both teams on 19 points and unbeaten. It is the first time the Catalans lead the league at the end of a fixture round since June 2020.
"We have to celebrate, they had won all their games, and we came back from a goal down; the team did great work and played a great game," said Arrasate.