City's unbeaten run continues, and Stuart Pearce has been singing the praises of his squad's never-say-die spirit.
For the second Saturday in succession the Blues came from a goal down to take all three points, with Claudio Reyna and Andrew Cole's strikes within three minutes of each other cancelling out Viafara's header.
City had again looked strong at the back, but the Portsmouth goal roused the whole side, and the fans with them, to inspire a stirring comeback which the manager says took a great effort from his side.
"Portsmouth made it difficult for us today," said Pearce after the game. "The two teams that have visited us this season have showed us a lot of respect by backing up behind the ball and making it difficult to knock them down.
"I thought when they got their noses in front it was going to be very difficult for us. All of a sudden we get a goal, and the game changes on its head. If you look over the 90 minutes, we deserved to win the game. The team deserve all the plaudits they get at the moment."
Pearce made a tactical substitution at the interval, bringing on Jihai Sun for Danny Mills, and the move looked to have worked despite the concession of the Pompey goal on 52 minutes.
"I thought Jihai might offer us a touch more going forward," explained Pearce, "Because they were banking up behind the ball, but he might get forward and get some crosses in. Danny took it in good spirit, but they all do. They all know any change I make is not a personal one, it is to win the football match."
But it is the refusal to give in and turn results around that pleases the manager the most, and he is already sensing that club could be in for a good decent given how the team have fought back of late.
"The spirit in the camp to not want to get beaten is sensational. If we can rekindle that and take it on right through the season we'll have half a chance of maybe finishing up the league somewhere. It is important we keep the team spirit in the camp, and couple that with the team shape and the ability of the individuals."