Joao Palhinha has picked up a suspected shoulder injury which cost him a transfer away from Fulham this summer.
The 28-year-old had to be substituted on the stroke of half-time of the Cottagers pre-season 3-2 friendly win over Brentford in Philadelphia on Sunday.
Palhinha, who has been the subject of a £45million failed bid from from West Ham, walked off with his arm in a makeshift sling in worrying scenes.
The Portugal international came off second best when contesting for a ball with Bees forward Yoane Wissa at the Lincoln Financial Field.
It left the ex-Sporting Lisbon midfielder writhing in pain on the floor, with Fulham medics rushing to his aid.
After receiving lengthy treatment, he was eventually escorted off by physios as he grimaced in agony, with his forearm popped up against his body inside his shirt.
According to the Daily Mail, Palhinha could have dislocated his shoulder.
It could scupper a potential move for Palhinha this summer, who impressed in his first season at Craven Cottage.
Along with West Ham, it is believed that Liverpool have him on their radar as a possible replacement for Saudi Arabia-bound Jordan Henderson.
And they could be the front-runners in landing him as talkSPORT understands that West Ham fear they have a slim chance in nabbing him.
David Moyes has made bringing in a defensive midfielder a top priority after Declan Rice joined Arsenal in a deal rising to £105m.
But the Hammers feel they will be priced out of a move with Fulham demanding north of £60m.
However any future move for Palhinha will depend upon the severity of his injury, with boss Marco Silva to be left sweating by the extent of his problem.
Silva had given Fulham fans a huge boost earlier on Sunday after he rejected a £40m offer from Saudi side Al Ahli.
Meanwhile the west Londoners are closing in on the £5.5m signing of Raul Jimenez from Wolves.
His imminent arrival could signal the end of Alexander Mitrovic’s time at Fulham, with the Serbian striker a target for Al Hilal.