Luis Enrique's team lost ground to La Liga leaders Real Madrid on Saturday as they were held to a 0-0 draw at Getafe.
Lionel Messi rattled the crossbar with a free-kick and the visitors missed a host of chances, although the combination of tenacious opponents, persistent rain and a tricky playing surface meant Barca struggled for their customary rhythm.
Sporting director Andoni Zubizarreta told reporters: "We didn't pass the ball quick enough, although we had chances and failed to make the most of them.
"We played our classic game with a 4-3-3, but Getafe didn't give us much room.
"The ball bobbled for long spells, and the water made [the pitch] become unstable. We didn't find much help out there."
Neymar missed the trip to Getafe due to a minor ankle injury and is unlikely to be risked against Huesca, while the Brazil star's compatriot Dani Alves is also sidelined with a hamstring problem.
It is unlikely Luis Enrique would have selected either man in any case, with a combination of youngsters and squad players primed for a run-out against the Segunda Division B team.
Barca hold a 4-0 advantage from the first leg, as goals from Ivan Rakitic, Andres Iniesta, Pedro and Rafinha a fortnight ago made progression to the round of 16 something of a formality.
Iniesta and Rafinha were named among the substitutes at Getafe so could start in midweek alongside goalkeeper Marc-Andre ter Stegen, who has played all Barcelona's cup games this term since signing from Borussia Monchengladbach.
Following their moment in the Nou Camp spotlight, Huesca will turn their attentions towards trying to secure promotion from a fiercely competitive Segunda B, Group 2.
Heading into this weekend's fixtures, a solitary point separated the top five, with Huesca second behind leaders Athletic Bilbao B on goal difference.
And Luis Tevenet's team moved to the top of the pile in emphatic fashion with a 6-1 win over Trival Valderas, rediscovering their scoring touch after goalless draws against Conquense and Fuenlabrada followed the Barcelona reverse.
