Liverpool kept Firmino on bench against Barca in the first leg of their Champions League semifinal on Wednesday.
Firmino had trained on Tuesday morning after shaking off a muscle strain but was picked as a substitute at Camp Nou, while Joe Gomez came in at right-back to make his first start since breaking his leg in December.
For Barcelona, Philippe Coutinho was preferred to Ousmane Dembele in the front three, the Brazilian taking his place alongside Lionel Messi and Luis Suarez against his former club.
Arturo Vidal was a surprise pick ahead of Arthur Melo in central midfield, with coach Ernesto Valverde opting for extra solidity against Liverpool’s pacey attack.
Starting line-ups for the Champions League semifinal, first leg between Barcelona and Liverpool at Camp Nou on Wednesday (kick-off 1900 GMT):
Marc-Andre ter Stegen; Sergi Roberto, Gerard Pique, Clement Lenglet, Jordi Alba; Sergio Busquets, Ivan Rakitic, Arturo Vidal; Lionel Messi (capt), Luis Suarez, Philippe Coutinho
COACH: Ernesto Valverde (ESP)
Alisson Becker; Joe Gomez, Joel Matip, Virgil Van Dijk, Andy Robertson; James Milner (capt), Fabinho, Georginio Wijnaldum; Mohamed Salah, Sadio Mane, Naby Keita
COACH: Jurgen Klopp (GER)
REFEREE: Bjorn Kuipers (NED)