Brentford striker Scott Hogan will miss most of the season after injuring the anterior cruciate ligament in his left knee.
The 22-year-old, who joined the Championship newcomers from Rochdale this summer, suffered the injury in the 2-0 win at Rotherham on Saturday.
"The most important aspect is his long-term health and recovery," Bees boss Mark Warburton told the club website.
"Scott will be carefully looked after by our outstanding medical team."
Hogan, who scored 19 goals in 40 appearances for Rochdale last season, suffered an ankle problem in pre-season and was making only his second appearance for Brentford at the weekend.
He is due to undergo reconstructive surgery on his knee next Wednesday.
"Timescales for Scott's return are loose at this stage. However, on average, the recovery from this type of injury is around nine months," Brentford head of medical Neil Greig said.
"Scott's injury will require some careful management. We have a young and talented player who has already demonstrated a positive attitude and determination to return better than ever."
Brentford strengthened their attacking options with the loan signing of Sporting Lisbon forward Betinho on transfer deadline day.