An injury-time header from Clement Lenglet gave Barcelona a 1-0 win over Cultural Leonesa in the first leg of its Copa del Rey last-32 tie on Wednesday.
Four days on from its 5-1 thrashing of Real Madrid, the Catalans struggled for inspiration in the absence of the injured Lionel Messi and rested stars Luis Suarez and Philippe Coutinho against their third-tier opponents.
It was Cultural who missed the better of the opportunities to earn a first-leg advantage to take back to Camp Nou in December until the first minute of second-half stoppage time, when Lenglet scored his first goal for the club.
Denis Suarez had the chance to add a flattering look to the scoreline deep into stoppage time but pulled wastefully wide, while the otherwise impressive Cultural midfielder Sergio Marcos received a second yellow card for dissent.
Ernesto Valverde handed chances to Ousmane Dembele, Malcom and Arturo Vidal alongside several youngsters, including centre-half pairing Chumi and Jorge Cuenca and left-back Juan Miranda.
The best chance of a poor first half fell to Zelu, who was denied by Jasper Cillessen after Nelson Semedo was dispossessed near his own penalty area.
Barca were then dealt a blow when Sergi Samper, so unlucky with injuries over the past two years, was left in tears on the touchline after being forced off with a calf problem.
Cultural continued to cause problems for Barca, who themselves looked sluggish in possession and short of creativity, with a wayward Dembele free-kick summing up their performance in the first hour.
Cillessen made a fine one-handed stop to keep out Saul Gonzalez's rasping drive and deny Cultural a famous win, and Barca grabbed a goal in the dying minutes with their only clear-cut chance of the match, Lenglet heading past Jorge Palatsi as Dembele got his dead-ball delivery right.
What does it mean? Shock risk will leave Valverde worried for second leg
If this was a chance for Barca's fringe players to stake a claim for a place, they failed to take it.
There was little to no fluidity about their play and the way Cultural approached the match will give it at least some hope of producing a real shock when it heads to Camp Nou for the second leg in a month's time.
Whether the likes of Dembele or Malcom feature remains to be seen, but it is unlikely Valverde will be pleased with the display.
Lenglet bails out Barca
This was not a performance Valverde will be proud of, but he can be pleased with the contribution of Lenglet, who added much-needed composure to his side before scoring the winning goal.
Complacent Semedo almost costs Barca
Few visiting players truly performed to their best of their abilities, but Nelson Semedo's casual moment in possession gifted Cultural arguably its best chance of the match. It summed up a generally poor display.
Barca have a tough run of games before the visit of Cultural to Camp Nou on December 5. Next up is a LaLiga trip to Rayo Vallecano, with a Champions League clash at Inter to follow, before domestic matches against Real Betis and Atletico Madrid.