Barcelona played at a 0-0 draw at Huesca, as Ernesto Valverde made 10 changes to the side that beat Manchester United in midweek in the Champions League.
Only Marc Ter Stegen kept his place from the 1-0 victory at Old Trafford, as La Blaugrana prepare for Tuesday's second leg at the Nou Camp.
In a first half of few chances, Ousmane Dembele and Jeison Murillo both tested home goal keeper Roberto Santamaria, with Huesca forward Eric Gallego blasting the hosts effort wide just before the break.
Barcelona looked to find a breakthrough after the restart, with Dembele again threatening to score, but the home defence excelled in shutting down space for the Barcelona attack.
Valverde brought on Jordi Alba and Philippe Coutinho in the closing stages to try and steal a win, but bottom of the table Huesca held firm, as Barcelona's lead at the top was reduced to nine points.