Pompey are missing several key men for Saturday’s trip to Rotherham.
The midfield is particularly bare, with Stuart O’Keefe now set to miss 10-12 weeks after undergoing an operation on a troublesome groin injury.
It comes after the news that Danny Rose is set to miss the rest of the campaign, having broken his leg against Northampton at the end of last month.
And with Gareth Evans not quite ready to return, Kenny Jackett will have to ponder how to fill those spaces.
The Blues boss said: “We’ve had a lot of injury problems across our midfield and so putting Nathan Thompson in there last week helped us.
“So the formation we used last time with three at the back is an option, although systems aren’t the most important thing.
"I don’t think we’ve been strong enough as a collective in the centre of the pitch with those disruptions and that’s something to look at."
“It’s also about things like attitude, body language and that personal drive to be as successful as you can.
“There’s a lot of experience missing in that area when you look at the likes of Danny, Stuart and Gareth.
“It’s very important to adapt when you lose those players and it means plenty of younger players have been given opportunities.
“They’ve impressed on an individual basis, but I don’t think we’ve been strong enough as a collective in the centre of the pitch with those disruptions and that’s something to look at.”
Pompey will face a Millers side who are one place – and a single point – behind them in the League One standings.
Jackett side: “They are another side who have play-off aspirations like us – and quite rightly.
“A lot other clubs will be looking to break into that group as well, so it’s going to be a real race for the top six over the next few months.
“Rotherham have been up there the whole season and will be looking to bounce back to the Championship at the first attempt.”
Jackett will be making his first visit to New York Stadium since ending a 39-day spell in charge there in November 2016.
He said: “I don’t bear any grudges to anyone there, but all of my focus is on Pompey and we’re playing one of our rivals.”