Barcelona have a mountain to climb to retain their Copa del Rey title after the Catalans slumped to a 2-1 home defeat in the first leg of their last-16 tie with Sevilla.
Pep Guardiola's men need to do it the hard way if they are to claim a 26th cup title after a weakened side went down to a much-altered Sevilla.
Injuries and international call-ups had left Sevilla coach Manolo Jimenez with just 14 seniors players for the trip, but the Andalusians came out on top thanks to second-half goals from Diego Capel and Alvaro Negredo, who netted the winner from the spot.
In between those strikes Zlatan Ibrahimovic, who started the match on the bench along with regular first-teamers Xavi, Carles Puyol, Thierry Henry, Victor Valdes and Gerard Pique, drew Barca level on 74 minutes.
Although Guardiola opted to leave many of his stars on the sidelines at the start, he still selected a decent team including Andres Iniesta, Dani Alves and Lionel Messi, and it was the Fifa World Player of the Year who came close to breaking the deadlock during a goalless first half when he hit the woodwork in the 22nd minute.
It was Sevilla who would end up taking the lead, though, as Capel picked up a pass from Renato Dirnei before beating Jose Pinto on the hour.
Barca were back on level terms 14 minutes later when Ibrahimovic, who replaced Pedro Rodriguez at half-time, scored his 13th goal of an impressive first season with the European champions since his big-money summer switch from Inter Milan.
Parity lasted barely two minutes, though, as Sevilla had the chance to get their noses back in front when Dmitro Chygrinskiy fouled Capel inside the area to concede a penalty.
Striker Negredo stepped up to slot past Pinto to give the 2007 cup winners a crucial lead to take back to Seville for next week's second leg.
The seven other last-16 cup ties will be played today and tomorrow.
Valencia and Deportivo La Coruna play at the Mestalla tonight knowing the winner of their tie will meet either Barca or Sevilla in the quarter-finals, while Villarreal and Atletico Madrid face Segunda Division opposition in the form of Celta Vigo and Recreativo Huelva, respectively.
Also in action are Real Madrid's conquerors from the previous round, Alcorcon, who face Racing Santander.