Liddle left Meadow Lane on Saturday evening wearing a protective boot after being hurt in a challenge with Robins defender Greg Cunningham during the 1-1 league draw.
Magpies manager Shaun Derry fears the 27-year-old may have damaged ligaments but he will undergo scans on Monday to determine the extent of the problem, although the club are optimistic there is no broken bone.
Derry has refused to put a timescale on Liddle's absence until the results of the X-rays are in, but the player looks likely to miss County's games over the Christmas and New Year period.
"Gary's struggling with his ankle," Derry told the media on Monday morning.
"I felt it was a bad tackle at the time, I've got to say, and after seeing it again on replays that has just clarified my view.
"He will be out of the next couple of games at the very least, but he's an honest guy and he'll get back as soon as he possibly can because he's a proper man.
"It doesn't look like a break, so we'll have to wait to see exactly what the damage is.
"It's a tough knock for the lad, but he'll bounce back. Hopefully he won't be out for too long because he's been immense for us, since the minute I walked through the door, he's been fantastic."
- Sports & Recreation
- Disease & Medical Conditions
- Shaun Derry