Hércules 1-1 Barcelona
Holders Barcelona were held to a draw at third-tier side Hercules in the first leg of their Copa del Rey last-32 tie on Wednesday.
David Mainz slotted in from close range in the second half to give the Segunda Division B side a shock lead.
But teenager Carles Alena drilled in from outside the box to level for Barca, who were without star forwards Lionel Messi, Luis Suarez and Neymar.
Barcelona next face arch rivals Real Madrid in La Liga on Saturday.
The champions will go into El Clasico (kick-off 15:15 GMT) in second place in the table, six points behind Zinedine Zidane's leaders.
Luis Enrique's Barca side have now drawn their last three domestic matches, following league draws with Malaga and Real Sociedad.
The second leg against Hercules takes place at the Nou Camp in three weeks' time on Wednesday, 21 December.
Meanwhile, Atletico Madrid thrashed third-tier side Guijuelo 6-0 in their first leg tie, with Yannick Ferreira-Carrasco scoring twice for Diego Simeone's side.
Pick the best Barca-Real Madrid XI
Imagine you could pick from the combined squads of Barcelona and Real Madrid - tasty but testing. Who would you choose?
- 1Buigues Rico
- 5Rojas Olmedo
- 3PenaBooked at 90mins
- 7López GasparSubstituted forFlores Gómezat 71'minutes
- 10Espinosa Valenzuela
- 11SalinasSubstituted forMiñanoat 71'minutes
- 9Mainz NavarroSubstituted forBerrocalat 79'minutes
- 12Bueso Paradís
- 14Flores Gómez
- 23UmtitiSubstituted forPerdomo Borgesat 69'minutes
- 30CarbonellSubstituted forAndré Gomesat 69'minutes
- 6D Suárez
- 28AleñáSubstituted forCardonaat 76'minutes
- 21André Gomes
- 31Perdomo Borges
- Daniel Ocón Arráiz
- Shots on Target