Northern Ireland national team captain Steven Davis will not play for his country during their friendly international with South Korea on Saturday.
Davis has had to miss Southampton's last five games due to a hamstring injury and has remained in England rather than reported for duty for his country.
While discussing the injury situation, O'Neill said: "It's been a wee bit tricky. Davo [Davis] is out, we've doubts over Niall, we've doubts over Kyle and checking a little bit on Stuart as well.
"We have to be careful with the players given the time of year it is and the nature of the game.
"The game will provide an opportunity for some of those players like Jordan Jones and Jamal Lewis and one or two others."