Plymouth Argyle midfielder River Allen could require knee surgery after injuring his medial ligaments.
The 19-year-old, who was on loan at Truro City, came off after 19 minutes of their and has gone back to his parent club.
"He's hurt his medial ligaments so he's no longer with us. He'll probably need an operation," Truro manager Steve Tully told BBC Radio Cornwall.
Allen played five times for Truro in the Southern Premier League.
"Gutted to miss the rest of the season with @TCFC_Official due to injury! Fingers crossed it's not too long, hope the boys get promotion," Allen posted on Twitter.