Table-topping Pompey extended the gap to third place in League One with victory at Wycombe.
While they were enjoying a 3-1 triumph on Good Friday, promotion rivals Bolton, Peterborough and Barnsley all dropped points.
A deflected Colby Bishop finish opened the scoring early on, only for the Chairboys to hit back through Matt Butcher.
But Bishop struck again for John Mousinho's in-form side before Christian Saydee finished the home side off after the break.