Newcastle midfielder Jack Colback will undergo a second scan of Thursday in order to determine the full extent of the knee injury he suffered in the Tyne-Wear Derby.
Newcastle assistant manager Paul Simpson said: "We don't know the full extent of the damage. He was obviously very sore when it happened. He has had one scan and has a second later in the week, just to find out exactly what the damage is.
"I have to say I didn't think it was a bad challenge. I don't lay any blame on Cattermole for the challenge. It was one of those whole-hearted tackles that you see in derby games, that we all want to see.
"It was just unfortunate that Jack took the brunt of it, the way his standing leg was, taking the full force of it."