Nottingham Forest boss Steve Cooper has confirmed a groin injury for Taiwo Awoniyi.
The Nigeria international was injured in the World Cup qualifier against Lesotho.
"It's bad news on Taiwo, he's had to have surgery and he is going to be out for months," said Cooper ahead of their clash with Brighton.
"We'll support him and try to get him back as quick and as fit as he can be, but it's a really unfortunate situation and a blow for him.
"He's become an important player for us with the goals he's scored and the goals he will score for us, but he's such a good guy and a good professional who is desperate to do well, so to get an injury like this is harsh on him.
"We've got to support him through the process of coming back stronger. He's done that once before here and I'm sure he will give everything again like he did last time.
"You think about how well he did when he returned last season, I'm sure that's given him a good reference point to come back to.
"We'll definitely see him again this season, but it's groin surgery so it will take a little while."