The Blues went down to a 2-1 loss to the Premier League side at Fratton Park in front of a crowd of 7,182.
But Jackett’s side matched their opponents for long periods in a useful test ahead of the new campaign.
And the Pompey boss believes his team are shaping up well ahead of the League One opener against Rochdale on August 5.
He said: ‘We gave them a good test.
‘You can see how quick, how good and how powerful Premier League players are.
‘It shows you how far we have to go, but I was pleased with the application of our players.
‘It’s hard to judge sometimes when you jump from non-league to Premier League opposition.
‘But I was pleased with the team and their attitude and understanding. The signs are good.’