Captain Virgil van Dijk did not travel with the squad for the start of their USA preseason tour as he remains away on a delayed summer break after the 2026 FIFA World Cup.
He could link up with Iraola's charges further down the line in North America, but Joe Gomez's participation in the tour is under threat, following another injury setback.
Gomez was forced off after just 10 minutes of Liverpool's opening 4-2 win over Sunderland and was replaced by 18-year-old Ifeanyi Ndukwe.
Giovanni Leoni is still some time away from returning, following an ACL injury, and Iraola confirmed he has little choice but to take it slowly with new signing Jeremy Jacquet following shoulder surgery.
Ndukwe is expected to feature more for Liverpool in preseason - alongside fellow 18-year-old Mor Talla N'diaye - but he's not eligible to play in the Premier League.
As per reports from The Athletic, he's not available to play top-flight games due to a lack of required points on his work permit to be involved in Liverpool’s first team in the upcoming campaign.
Iraola could now be forced to dip into the transfer market to sign a new defender before his season start against Newcastle United on August 23rd.