Joe Gomez's preseason injury has deepened concern, alongside Giovanni Leoni and Jeremy Jacquet not yet being back to full fitness, and fears over game load on club captain Virgil van Djik.
Conor Bradley is also not expected to be ready for the start of the campaign and Jeremie Frimpong picked up a knock on the USA tour - alongside Andy Robertson and Ibrahima Konate's summer departures.
Despite the concerns over defensive depth at Anfield, Liverpool are not planning to make a move for former centre-back Jarell Quansah, despite an agreement being in place with Bayer Leverkusen.
The Reds have an option to bring him back for £70M, but talkSPORT have reported they are not interested in a reunion, as Iraola plots his next move.
Iraola has three more Anfield friendlies to fine tune his squad before their Premier League campaign opener at Newcastle United on August 23rd.