He missed two matches upon his return before starting against Brentford earlier this month, only to be forced off again after reaggravating the injury with barely half an hour played.
Jeremie Frimpong picked up a muscle injury there, too, which is set to keep him out for several weeks, while Munoz suffered a knee injury and has not featured since. Florian Wirtz, meanwhile, picked up a knock in last weekend’s defeat of Brighton.
Iraola is not confident all four will be able to feature against the Blues in this last-16 clash.
Sidelined: Dominik Szoboszlai
PA
“We still have to wait,” he told reporters at his pre-match press conference.
“We train later. Florian (Wirtz) was quite fine and optimistic he would be available.
“With Dom (Szoboszlai) and Victor (Munoz), I'm not so sure. I don't want to say no, but I think it's more difficult than Florian.”
That is a considerable blow for Liverpool, though Chelsea are in the same boat. They are expected to be without Joao Pedro and Reece James at Anfield.
Iraola continued, saying he expects it to be a physical battle against the Blues, managed by his close childhood friend Xabi Alonso.
“Nowadays all the teams are quite intense, not just sitting in a block. They want to press, and there won't be many spaces.”