Iraola said before the 22-day break after the Manchester United game that he was hopeful Cook could use that interval to return, but the midfielder will not be back for the trip to Arsenal.
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There was good news elsewhere in the squad, though, as the Englishman is now just one of two injured players for Iraola’s side, along with Justin Kluivert.
Iraola said: “Lewis Cook is taking maybe more time than we expected and he's not there yet, but I think everyone else is available.
“There are some cases, especially Julio Soler. Julio Soler is not ready to play a lot of minutes, but he's training at least with the group and I think he's kind of recovered.
“And everyone else I think is ready.
Tyler Adams (Image: Richard Crease)
“I think cases of Tyler, of Ben Doak, they've used this kind of break to put themselves again in contention and I think we are in a good place.
“I will even have to make difficult decisions, but because probably we will be more than 20 ready to travel.”
Iraola also gave an update on those who returned early from international duty.
“I would add Junior Kroupi and Alex Jiménez came from the national team with some niggles,” he said.
“It was more precautionary and they've had some rest also with us, but they are fully recovered and are ready to go for tomorrow.”