As confirmed after the Carabao Cup win at Vicarage Road, Amankwah Forson is expected to be out for a number of weeks but scans have shown he won't require surgery.

"(Forson) doesn't require surgery so we're hopeful that'll remain the case and he has a smooth recovery. It could be a considerable amount of time. That doesn't mean he'll stop developing, we'll put some energy into the gym and video work," Manning said.

"You could see he was quite upset when he came off. He had been quite upbeat and enjoying himself."

Gabe Forsyth and Lucien Mahovo continue their rehabilitation with the view to joining first-team training in the next few weeks, with a target of the September international break mentioned.

Meanwhile, club captain Kenny McLean is 'responding well' to his treatment as he returns from a surgical procedure.

"On track, progressing well. (Gabe)'s out running. We're pleased with how things have gone, it'll still be a few weeks before he's back in with the team. Similar for Lucien, progressing nicely.

"(Kenny)'s doing really well. The challenge you always get is when you start to ramp up stages of their return, how will they respond."

Elliot Myles is still expected to be out for a bit longer while Ante Crnac and Mathias Kvistgaarden, left out of the squad at Watford, are both back in contention.

Two players that Manning spoke about were Kellen Fisher and Harry Darling after the Carabao Cup win.

Fisher was making his first start of the season while Darling has been one of the stand-outs for City through pre-season and the first couple of games of the campaign.

"(Kellen) did really well the other night, he got forward and supported attacks well. He showed a bit of bite which I liked, against a physical side like Watford. I like the competition, my job is to manage it and support it. If one of them is in front, my job is to sit with the other and say here is what you need to do," he explained.

"I worked with (Harry) at MK, his levels have gone up a considerable amount since then. You can see his quality on the ball, he's improved a lot on his defensive side of the game. You can see his leadership - when Papa made that tackle in the first half, he was the first to run over and celebrate with him. The non-sexy stuff that helps you win games, Harry's been key in reinforcing that."

With Portsmouth up next in a lunchtime kick-off on Saturday, Manning knows that their home record is something that has to be acknowledged.

City played out a goalless draw on the south coast last season while losing 5-3 at home in the reverse fixture.

"You'll ask me that most weeks and get a standard answer about how difficult the division is. You have to throw Fratton Park into the mix, how difficult a place it is to go and their home record. With the week we've had, it's one that we've got to be relishing," Manning added.

"Do you make wholesale changes to how you play? No. You have to acknowledge and respect the challenge you are going into, and then turn up and deliver."