Jamal Lowe will miss Pompey’s opening game of the 2018/19 campaign.
The winger injured his ankle in Saturday’s final pre-season friendly against FC Utrecht at Fratton Park.
He played just over an hour of the 1-1 draw against top-flight Dutch opposition before being replaced by Gareth Evans.
But Kenny Jackett revealed that the issue is not a serious one and the 24-year-old should return to action by the middle of August.
The Blues boss said: “It looks like his ankle strain might take two to three weeks to recover from – we hope it will be the better end of that.
"It could have been a lot worse, but Jamal is a quick healer."
“When you see him limp off the way he did then it could have been a lot worse, but Jamal is a quick healer.
“He just came down and landed awkwardly on the ankle. There’s a slight ligament strain and a little bit of swelling because of it.
“We’ve also got Dion Donohue as very unlikely, although other than that we’ve got full availability for selection, which isn’t too bad.
“I’ve been pleased overall with how we’ve fared in pre-season and the application of our players has been excellent.
“We’ve worked hard all the way through the summer and now we want to put some foundations down.”
It was a memorable weekend for Anton Walkes, who scored a spectacular goal against Utrecht before becoming a father a few hours later.
Jackett said: “Congratulations to Anton. He’s settled in the area after being here on loan last season. I’m sure that will help him as he gets used to a new baby in the house.”