The Nigeria international has been sidelined since sustaining a hamstring injury during Celtic’s UEFA Europa League match against Austrian side Sturm Graz last month.
As a result, Iheanacho has missed the Scottish Premiership champions’ last four games across all competitions.
Speaking ahead of the weekend fixture, O’Neill confirmed that the former Manchester City striker is expected to remain on the sidelines for a few more weeks as he continues his recovery. T
“Yeah, he (Iheanacho) is going to be a few more weeks,” O’Neil said during his interaction with the media on Friday.
“I think that obviously after Sunday we’ve got this fortnight break and we’ll see how things go from there.
“But yeah, he certainly won’t be available for Sunday anyway.”