Nottingham Forest striker Chris Wood admits he will have to manage his knee injury for the rest of his life.

The New Zealand international has returned following six months out and is in line to feature in Forest's Europa League quarter-final second leg against Porto.

Forest host the Portuguese league leaders on Thursday following last week's 1-1 draw in Portugal, with Wood starting at Estadio do Dragao.

It was his first game since last October, having had knee surgery in December, and the forward knows his knee will never fully recover.

"It's a knee injury, it's going to take years of managing throughout my whole career and when I'm playing with kids, playing golf or doing whatever I do after football," said the 34-year-old.

"It's going be there. I'd say it's always got to be in your back of mind that I have to keep myself in top shape ready to go.

"A knee injury is always horrible, you never know what could happen in the future or how you are going to come back from it.

"So mentally, that's one of the tough things to deal with. But I had confidence I was always going to come back. I got very close to returning pre-surgery and it just didn't happen. That's just unfortunate."

Wood returned as he looks to help Forest into the last four of the Europa League - where they will face Aston Villa or Bologna - and stay in the Premier League.

He is also aiming for a World Cup spot with New Zealand, with the All Whites facing Iran, Egypt and Belgium in Group G in this summer.

"It wasn't a straightforward injury, we tried a few different avenues to get it right before having to go down the surgery route," added Wood, who did not play for Sean Dyche during the former manager's 114 days in charge of Forest.

"It didn't work out the way we wanted to. At least we got it now with a goal to come back to, and luckily I have been able to come back with a decent amount of time [before the World Cup], so hopefully I'll be in the running."

Midfielder Elliot Anderson is a doubt to face Porto after he missed training on Wednesday.

"Today, he was not able to train," boss Vitor Pereira said. "He has personal problems, and we have to respect [them]. We will see [about tomorrow], we need to wait."