O'Neill has called up 24 players for the Group F qualifier against Russia on Friday, with Kyle Lafferty and Chris Baird joining the squad for the game against Israel four days later after serving one-game bans.
In total, O'Neill's squad calls upon players from eight different divisions across England, Scotland, Greece and Switzerland, but he knows he cannot afford any of them to pick up injuries over the weekend.
Only Dean Shiels, of Rangers, is currently unfit for selection and, with three points from the first four games of the campaign, O'Neill does not want to any more withdrawals.
"I have pretty much everyone I want now and I just hope they come through the weekend unscathed," he told Press Association Sport.
"Most of our lads play today, which is good in terms of us getting them for a bit of work next week.
"But the main hope is not to lose any more players because we know our resources are limited, especially going up against this level of opposition."
One man who has been on the wrong end of numerous injury problems in Burnley striker Martin Paterson.
But O'Neill was glad to name him in yesterday's squad after the 25-year-old opted to end a self-imposed international absence, taken with the intention of getting himself back to peak fitness.
"At the time, Martin was in a difficult place injury-wise with his club and he's had a lot of problems in the last 12 months," O'Neill explained.
"In light of that he just felt at the time he needed to concentrate on his fitness and get a run of games together.
"He felt being involved at international level would not help and I understood that. I wanted to have him involved but he felt it was better to take himself out.
"We kept the dialogue open and I spoke to Martin soon after Christmas when he'd played for the best part of three months injury-free and he is happy to come back."
Paterson, who scored his first international goal from the penalty spot in his last appearance against Finland, still faces competition for a starting spot though.
Will Grigg has scored seven times in his last four matches, albeit in npower League One with Walsall, Billy McKay and Niall McGinn are enjoying prolific seasons in Scotland, and Jamie Ward has scored 11 times for Derby this term.
However, McKay, Grigg and Ward have just seven caps between them and McGinn has been used exclusively as a winger by O'Neill, leaving Paterson with a big chance.
"Martin is obviously a bit more experienced than the other options like William or McKay.
"They are both doing extremely well but are relatively inexperienced at international level. Martin has experience of the Championship and the Premier League and although he hasn't played as much internationally as we'd like, partly because of his injuries, he's certainly a nice option to have.
"Kyle's ban is an opportunity for someone to state their case."