Head coach John Plumtree confirmed there is "concern" around the 28-year-old's condition, though surgery has been ruled out at this stage and they expect him to be back for the URC playoffs.
Williams, who has earned 17 Test caps for the Springboks, has made 10 appearances this season across the United Rugby Championship and Champions Cup. He was not included in the squad for Saturday’s Round 16 victory over Ulster in Belfast.
He featured off the bench in their narrow 18-17 victory over Edinburgh the week before, but the injury resurfaced during his 31-minute stint on the field.
“We’ll have to investigate more,” said Plumtree. “It’s not serious enough for surgery, but we need to manage it properly.
“He has a facet joint injury that has bothered him for weeks.
“We rested him for weeks and we had him doing neck strengthening exercises.
“The injury has settled down. It is healing, but it is not right yet, and we have to give it a bit more time,” the Sharks coach added.
“He’ll be back for the play-offs. We will give him another three to four weeks to get that neck healed fully.”
Williams is widely regarded as the most talented scrumhalf in South Africa at the moment, so Sharks and Springbok fans will be hoping he returns to full fitness soon.
