Cardiff captain Mark Hudson looks set to miss three to four weeks of action and may require surgery on his injured ankle.
The 30-year-old defender was forced off at half-time in the Bluebirds' 1-1 draw with Derby with an ankle injury which forced him to miss the victory over Sheffield Wednesday.
"There is a complication and that's something we are looking into," manager Malky Mackay told the South Wales Echo.
"There are conversations needed with our medical people and I can't put a timescale on when Mark is back.
"It looks at least three or four weeks, but we still have to make decisions."
Mackay loaned in Norwich defender Leon Barnett last week and the former West Brom man looks likely to be a regular in the skipper's absence.
Korey Smith is set to make his Oldham debut as Lee Johnson starts his managerial career at Boundary Park against Pools.
Smith has joined the League One strugglers on a one-month loan deal from Norwich and is fit to feature against John Hughes' side.