Michael Appleton insisted Swindon represented a return to form for Pompey, despite their 2-1 defeat.
The hosts fell behind through Matt Ritchie’s strike on the stroke of half-time, before Andy Williams netted 10 minutes into the second half.
A barnstorming finish saw new-boy Lubomir Michalik net in the 90th minute to cap an impressive final 10 minutes from the Blues.
During that period, Michalik also hit the bar, Izale McLeod struck a post, while substitute Ashley Harris drew a tremendous save from Robins keeper Wes Foderingham.
Pompey eventually ended up empty handed as the full-time whistle spared the wilting Robins, with Paolo Di Canio’s men clinging on to their victory by the narrowest of margins.
The overall performance was enough to encourage Appleton, who believes it was an improvement in display compared to recent league games against Oldham, Crawley and Walsall.
For him it justified a change in formation, which saw Darel Russell and Lee Williamson operate as holding midfielders, with Jordan Obita, Brian Howard and Jack Compton playing behind lone striker McLeod.
And Appleton’s seeking to maintain the level of performance for the trip to Notts County this weekend.
He said: ‘I thought we looked a good side last night.
‘We contributed to what I thought was a really, really good game of football. It was quick, had a lot of energy, had a lot of good play, there were a lot of chances at both ends and it was an end-to-end match.
‘That is probably as good as we have been for the past four or five games.
‘I thought we passed the ball really, really well and looked a threat.
‘Certain players can play in all sorts of positions and it gives me a lot of belief and much comfort knowing we can create a lot of chances.
‘I am just happy with the way they (the players) reacted to going two down.
‘I wasn’t happy on Saturday against Walsall, even though we got a goal back.
‘Last night we pulled one back and I felt kept ourselves on the front foot and really tried to get something out of the game.
‘The players responded really well and dug themselves back into the game and, obviously, in the last 10-15 minutes there was only one team who was going to score a goal.
‘The spirit they showed in the second half proves there is a lot of belief and character in that dressing room.’
Despite two poor goals to give away against the Robins, Appleton was delighted with the attacking capabilities of his side.
However, he acknowledges the Blues didn’t make enough of the chances they created.
He added: ‘The first half they had a lot of opportunities from set plays and corners which kept us penned in a little bit, but I always felt we could score goals playing the way we were.
‘It was a bit of a killer blow conceding that first goal before half-time.
‘We started the second half well and then got sloppy from a throw-in and they get the second goal, which was a fantastic strike from Williams.
‘I thought it was a good game of football but we fell a little bit short because we couldn’t capitalise on the pressure we put on them at the end.’