Michael Owen could be out for a month after sustaining a groin injury in training with Newcastle.
The England striker is 50-50 for the clash with Manchester City on Monday.
The in-form striker tweaked a groin in training on Wednesday and faces a scan later today.
And Owen could be out for up to a month if the scan delivers bad news, according to interim manager Joe Kinnear.
He told the Evening Chronicle: "He tweaked his groin in training so he is a big doubt.
"It's 50-50 whether he plays for the Man City match. He is having a scan today.
"Then we will find out more, we are just assessing the situation.
"I am hoping it is not as bad as it looked when he first did it.
"I am hoping it may have calmed down but we are worried that if the scan shows a tear then he could be out for a month.
"Hopefully it won't be but we are in the dark until later on today."