Glen Fisiiahi's pectoral injury has potentially ended his 2013 National Rugby League campaign with the Warriors.
If it's as serious as suspected, it would also impact on his chances of being available for Tonga for the Rugby League World Cup in October-November.
Team doctor John Mayhew said further assessment was required but the initial diagnosis wasn't promising.
If it's confirmed Fisiiahi has torn the pectoral on his right side he would face a lengthy term in recovery.
Warriors prop Jacob Lillyman needed surgery after tearing his pectoral in the first trial of the season in early February.
He missed the first eight matches of the NRL campaign before returning in May.
The 22-year-old 'Fish' has had his best season since his debut in 2011 but a cloud hung over his immediate future when he left the field in the 60th minute of Friday night's 24-14 win over Wests Tigers at Leichhardt Oval.
After making eight appearances in 2011 and 2012, Fisiiahi has more than doubled his career tally to 19 matches, scoring five tries in his 11 games this year.
He also made his test debut for Tonga in April.