Sunderland defenders Phil Bardsley and Matt Kilgallon will not be joining the Black Cats on their tour of the Far East next week.
Martin O'Neill's side are due to fly to South Korea in the coming week to take part in the pre-season Peace Cup.
But neither right-back Bardsley nor centre-half Kilgallon will be on the plane.
O'Neill told the Shields Gazette: "Phil went over on his ankle and it's really sore. Nothing's broken, but he's done a bit of damage.
"He's very doubtful and I don't think the trip would be good for two things. One, he wouldn't be able to play and two, being back and forth on a plane would be no benefit.
"Matt had been trying to do some work himself over the summer to keep fit and he injured himself doing that. He came back with a bit of a problem, so the best thing to do is to leave him out."
O'Neill, meanwhile, plans to follow up his tentative interest in a couple of unnamed transfer targets.
He said: "I haven't done anything definite. I've made the enquiries and said to people, keep us informed. But now I will start to develop things a bit more."