Newcastle midfielder Joey Barton could be sidelined for several months after undergoing surgery on a foot injury.
Barton had exploratory surgery on his right foot on Thursday and the Magpies are now awaiting full details of the extent of the damage.
However, the club are confident the problem is not connected to Barton`s previous foot problems - he has suffered two metatarsal injuries in the past.
Argentina defender Fabricio Coloccini will also sit out the clash with Bristol City at St James' Park with a groin problem, but Ryan Taylor could return from a calf strain.
Striker Shola Ameobi remains on the sidelines with a foot injury and is expected to be out of action for up to two months.