Newcastle striker Callum Wilson will be sent for more scans at the end of this week when the club will learn the full extent of his injury.
Sportsmail understands they are yet to determine exactly how long the 29-year-old will be absent but further tests will give a more definitive timeframe and what treatment is required.
There is also a danger the injury has affected his Achilles, and the prognosis will have a significant bearing on the club’s transfer business this month.
Early suggestions that Wilson could be out for around six weeks with a calf injury have made way for concern that it could be longer.