United made former Swansea City centre-back Kyle Bartley one of their key targets of the summer but Bartley has joined West Brom and Leeds are yet to bolster their squad at the centre of defence.
Bielsa, though, has already used more recognised midfielder Kalvin Phillips as a centre back and the Argentine head coach has said that full backs Gaetano Berardi and Luke Ayling plus midfielder Conor Shaugnessy are other options in the position, in addition to first choice duo Pontus Jansson and captain Liam Cooper.
That said, United's boss admits he would also welcome another addition before the close of the summer transfer window and Leeds have been in talks with Everton about taking Matthew Pennington back for another season-long loan.
Asked if he felt he had enough options at centre-back, Bielsa said: "Berardi, Jansson, Cooper, Shaughnessy, Ayling. We have these players.
"Even if we have just Cooper and Jansson as centre-backs, Shaughnessy is a defensive midfielder but he can play as a centre-back too and Berardi is a full-back but he can play also as a central back. Kalvin Phillips also can play as a central back. Ayling has already played as a centre-back.
"But if we could add another option in the central defence it would be good too."
It remains to be seen whether or not Bielsa lines up with two centre-backs as part of a 4-1-4-1 system or whether the Argentine opts for three centre-backs as part of a fluid 3-3-3-1 formation that he used in the club's final pre-season friendly against Las Palmas.
Against Las Palmas, Phillips partnered Cooper and Berardi at the heart of the defence.
"Sometimes he has to play in different zones and positions on the pitch," said Bielsa of Phillips.
"For a defensive midfielder, for example, can become a third defender.
"It’s the result of the dynamics of the game and it’s also the product of a fixed scheme of three centre-backs.
"And Kalvin Phillips does not have any problems playing in either position.
"During the last pre-season, the team never played with three centre-backs, but during last season he did as the evolution of the game ordered it.
"Matters related to positions are flexible. And I don’t think they are very important."