Pompey have already faced three Championship sides as part of their pre-season preparations.
A narrow defeat at QPR’s training base earlier this month was followed by draws against Bristol City and Luton.
The latter contest at Kenilworth Road saw Gassan Ahadme almost immediately cancel out Elijah Adebayo’s early strike.
Danny Cowley was pleased with their efforts, but concedes that he still needs players to boost his squad.
The Blues boss said: “It was a challenging game and Luton asked a lot of questions, but we managed to find some answers.
“There was a real resilience, determination and grit from us and that can only help us as the season unfolds.
"It was a challenging game and Luton asked a lot of questions, but we managed to find some answers."
“We’ve had three games against Championship teams now and when you look at how we did when the first eleven were on the pitch, we beat QPR and Bristol City, then drew with Luton.
“That bodes well and so now the important thing is for us to get some support for those players – we know exactly what we need.
“We’re looking for power, pace and athleticism to help the talented guys that we’ve already got in this group.”
Cowley was pleased to see a healthy number of Pompey fans make up the noisy crowd in Bedfordshire.
He said: “It was amazing to see our supporters back inside the ground again – just as it was at Havant & Waterlooville.
“A few hundred travelled up to watch us in a pre-season friendly and we’re so appreciative of their backing.”
Pompey are waiting to assess new signing Jayden Reid, who went off in the closing stages after suffering a contact injury.