There are fears Cagliari midfielder Sebastian Eriksson snapped his anterior cruciate ligament while playing for Sweden.
The Swedish international collapsed in agony during a training session in Gothenburg on Friday.
According to the latest reports, Eriksson has a suspected anterior cruciate ligament injury with the meniscus also potentially damaged.
He will need to undergo further tests and surgery is very likely.
The 25-year-old is expected to be out of action until at least January 2015, possibly more depending on the extent of the damage.
Watch Serie A live in the UK on Premier Sports for just £9.99 per month including live LaLiga, Eredivisie, Scottish Cup Football and more. Visit: https://www.premiersports.com/subscribenow