The Blues midfielder made a surprise return to the side at the County Ground, having missed Saturday’s defeat to MK Dons with a groin injury.
Pompey had feared Close could be sidelined for up to four weeks, which would have meant he’d miss the rest of the season.
The Southsea lad was unable to help the Blues arrest their faltering League One play-off push against the Robins, though.
Danny Cowley’s side lost 3-1 at relegation-threatened Swindon, meaning Pompey have picked up just one point in their past four matches and dropped to eighth in the table.
Close featured for 81 minutes before being replaced by Andy Cannon.
And although the academy product was left bitterly disappointed by the result at Swindon, he’s happy to be back to full fitness and available for the final four crucial games of the campaign.
Close said: ‘It was a build-up of playing games close together over a few weeks and not having that recovery after going a long time after not playing football.
‘Naturally, there is inflammation and fatigue in there. It didn't feel good on Wednesday, Thursday or Friday so the gaffer and the medical team put a plan together.
‘I pulled out of MK Dons, which ended up being the correct thing. I turned up to training Monday feeling pretty good and then I was told I had a scan in the afternoon.
‘The plan was to make sure it was all clear, which I thought it would be.
‘There was a bit of inflammation, no damage or tear, then trained Monday evening and was all good.’