Derby County striker Nathan Tyson could be sidelined until the middle of November after another injury setback, reports BBC Radio Derby.
Tyson was due to play in a friendly against Chesterfield on Wednesday but had to pull out with a groin injury.
It is thought the latest problem is different to the groin injury Tyson suffered in pre-season.
Leading goalscorer Steve Davies was earlier this week ruled out until January with a fractured skull.
Tyson was forced off in the first half of the pre-season game against Aston Villa but featured as a substitute against Nottingham Forest last month.