Glenavon manager Marty Quinn says defender Mark Haughey will not play again this season after breaking his leg in a league game last Saturday.
The 20-year-old fractured the tibia and fibula in his right leg playing against Coleraine and has been discharged from hospital after an operation on Sunday.
"It is a big blow for us, losing a young up and coming centre-half, who has been playing well," said Quinn.
"We will not rush him. It is a matter of returning for the next pre-season."
Bottom-placed Glenavon got their first win of the season in the match against Coleraine and are now two points behind Carrick Rangers.
Quinn's men are at home to Glentoran in the Premiership this Saturday.