Alba was taken off in the 74th minute of Tuesday's Champions League contest with a hamstring issue, while Pedri played a full part on his return to action following a three-week rest.
Barca announced on their official website on Wednesday that Pedri is suffering with a thigh problem and has joined Alba in the treatment room ahead of Tuesday's (AEST) LaLiga clash with Granada.
No timeline has been given for both players' return to action.
"The first team player Pedri has a quadriceps muscle injury in his left thigh," Barca revealed. "The player is unavailable for selection and his recovery will dictate his return.
"Tests carried out on Wednesday morning on the first team player Jordi Alba show that he has a hamstring injury in his right thigh.
"The player is unavailable for selection and his recovery will dictate his return."
Barca's injury issues are piling up ahead of a busy spell of five games in a fortnight, including a huge clash with LaLiga champions Atletico Madrid early next month.
Martin Braithwaite is expected to miss the rest of 2021 after undergoing knee surgery, while fellow attackers Sergio Aguero, Ousmane Dembele and Ansu Fati are also out of action.
According to Spanish outlet Marca, Barca boss Ronald Koeman feels the club's medical department are partly to blame for the growing list of absentees.
The loss of Alba will leave a big void to be filled in the troublesome area of left-back, with academy product Alejandro Balde coming on for his senior debut in the heavy defeat to Bayern.
Pedri has also been a regular under Koeman over the past 13 months, making 55 appearances in all competitions since the start of last season – only Youssef En-Nesyri (57) and Manu Trigueros (59) have been used more often among LaLiga clubs.