Philippe Coutinho scored a crucial away goal but Barcelona have work to do to avoid a surprise exit from the Copa del Rey after losing 2-1 to Levante on Thursday in the first leg of the last 16.
Lionel Messi, Luis Suarez and Marc Andre ter Stegen were among several key players rested at the City of Valencia Stadium, where Levante took advantage as Erick Cabaco and Borja Mayoral gave them a two-goal cushion.
Coutinho, however, making his first start in almost a month, converted an 85th-minute penalty to leave Barca in touch heading into next week's second leg at the Camp Nou.
"When (Ousmane) Dembele didn't play, everyone asked about him, now Coutinho doesn't play, it's the reverse," Valverde said afterwards. "When you don't play and you aren't happy, you have to fight to change things."