Barcelona's La Liga title hopes were hit as they followed up their famous Champions League win over Paris St-Germain with a defeat at struggling Deportivo La Coruna.
Luis Enrique made five changes from the side who beat PSG 6-1, with the injured Neymar ruled out.
Barca were below par, falling behind to a close-range Joselu finish.
Luis Suarez equalised seconds after the restart but an Alex Bergantinos header sealed Depor's win.
Real Madrid will go top by two points if they beat Real Betis at 19:45 GMT, while Zinedine Zidane's side will still have a game in hand on the defending champions after that.
Barca back to earth with a bang
Barcelona had produced one of football's famous comebacks on Wednesday after scoring three times after the 87th minute to beat Paris St-Germain 6-1 - 6-5 on aggregate - in the Champions League last 16.
But those heroics seemed to have taken it out of them and they missed Neymar, who scored two and assisted the other of the late goals against PSG.
Pepe Mel's Deportivo, who are one place above the relegation zone, deserved to win, and also went close to a goal when Alejandro Arribas' header was tipped onto the post by Marc-Andre ter Stegen - with Bergantinos' winner coming from the resulting corner.
Lionel Messi, who failed to score for the first time in six games, fired a late free-kick over as they possibly lost the edge in the title race.