Leicester Lions reserve Simon Nielsen faces a lengthy spell on the sidelines after breaking his leg in Saturday's 53-43 win over Plymouth.
The Dane broke his femur after colliding with team-mate Jari Makinen.
Co-promoter Alan Jones, whose side are second in the Premier League table, said: "It was our best win of the season at home and yet came at a cost.
"Simon has been a model pro, a team player and a delight to have. He'll be sorely missed and hard to replace."