10-man Barcelona were held 0-0 by Rayo Vallecano in their opening game of the La Liga season at the Spotify Camp Nou as skipper Sergio Busquets was sent off.
The Catalans had 21 shots on goal and the majority of possession but were unable to break the deadlock.
Barca boss Xavi started close-season signings including defender Andreas Christensen, winger Raphinha and striker Robert Lewandowski, who were only able to feature after being registered with the league late on Friday.
The five-time Champions League winners had to comply with La Liga's strict financial controls before being able to confirm the likes of ex-Bayern Munich attacker Lewandowski in their squad ahead of the new campaign.
"We could have won, but now we have to correct our mistakes and think about Real Sociedad next weekend," said Barcelona defender Eric Garcia.
"We wanted to start the season on the right foot and with a victory, but we knew that Rayo gave us a lot of problems last year. They were good defensively tonight."
The hosts dominated the opening half an hour as Lewandowski was denied a goal on his competitive debut.
Polish forward was judged to be offside from an Ousmane Dembele pass before his delicate chipped finish was cancelled out.
As rain fell at the Camp Nou in temperatures of 26 degrees Celsius (79 degrees Fahrenheit) Pedri came close to breaking the deadlock with 10 minutes of the half to play but his curling effort flew past the post.
Despite their first-half control Marc ter Stegen ensured the sides stayed level at the break with a fine save to stop Rayo's Alvaro Garcia during injury time.
Barca continued their onslaught on the Rayo defence but were unable to beat goalkeeper Stole Dimitrievski, who was involved in two heavy collisions on his line within the first 10 minutes of the second half.
With half an hour to play, Xavi brought on Frenkie de Jong for Gavi despite the Netherlands midfielder being linked with a move away from Catalunya to lighten club debt, which forced Lionel Messi to leave 12 months ago