Bielsa told reporters at a press conference that while there could be new additions to his side, he is happy that midfielders such as Kalvin Phillips can drop into the centre-back role if needed.
"Even if we have just Cooper and Jansson as centre-backs, [Conor] Shaughnessy is a defensive midfielder, but he can play there, as can Berardi as a full-back," the Argentine said.
"Kalvin Phillips can also play as a centre-back. Ayling already played as a centre-back. If we could add another option it would be good too."
Leeds, who begin their season at home to Stoke City on Sunday, are expected to be without Jansson, who had a late start to pre-season after reaching the quarter-finals of the World Cup with Sweden.