View the photos from the Blues' Bescot Stadium success
Pompey survived a late Walsall fightback to secure a 3-2 victory and boost their League One promotion hopes.
When Nathan Thompson was shoved inside the box, skipper Brett Pitman stepped up to coolly convert the penalty.
Jon Guthrie converted a couple of late corners to give the Saddlers hope, but the visitors saw out the closing stages.