The defensive duo were late arrivals for Barcelona over the summer, and they have not yet been involved for the Catalan giants.
The pair are in the squad for Saturday's affair with bottom-of-the-table Cadiz, though, and Xavi has been able to name a strong selection.
Sergi Roberto is the only first-team absentee, with the Spaniard picking up a slight muscular problem during the Champions League clash with Viktoria Plzen on Wednesday night.
"He is performing very well, I am very happy, a very important wildcard for the team, he can play in any position, without complaining. He has a little discomfort... maybe he doesn't travel to Cadiz, but for the Champions League," said Xavi when questioned ahead of this contest.
Bellerin's arrival from Arsenal was crucial due to the team's lack of options at right-back, but Alonso faces competition from Jordi Alba and Alejandro Balde at left-back.
Barcelona were held to a goalless draw by Rayo Vallecano on the opening weekend of the new La Liga season, but they have since won their last three against Real Sociedad, Real Valladolid and Sevilla.
The Catalan outfit will enter this match off the back of a Champions League success, meanwhile, recording a 5-1 win over Viktoria Plzen at Camp Nou.
Xavi is expected to recall the majority of his key players for the clash with Cadiz despite the fixture coming ahead of a European contest with Bayern Munich.
Robert Lewandowski has now scored eight times in his last four appearances for Barcelona, and the Poland international is expected to start this weekend.
Ousmane Dembele, Ansu Fati, Ferran Torres, Memphis Depay and Raphinha are also options in the final third of the field for the Catalan outfit.
Miralem Pjanic's recent departure has opened up a squad role in midfield, meanwhile, and there is a spot in the squad for 19-year-old Pablo Torre, who joined the club from Racing de Santander over the summer.
Barcelona squad vs. Cadiz: Ter Stegen, Pena, Tenas; Bellerin, Pique, Araujo, Christensen, Alonso, Alba, Kounde, E Garcia, Balde; Busquets, Pedri, Kessie, Torres, De Jong, Gavi; Dembele, Lewandowski, Fati, F Torres, Memphis, Raphinha