The Irishman bagged his 10th goal of the season as he returned to the starting line-up in place of the injured Michael Jacobs.
Curtis opened the scoring in the eighth minute when he coolly converted at the back post after John Marquis flicked on Charlie Daniels' free-kick.
The Blues had to wait until 64th minute to double their advantage. Ellis Harrison converted from the penalty spot after Ryan Williams was fouled.
In truth, Pompey scarcely looked troubled throughout the contest, with keeper Craig MacGillivray having little to do.
Curtis was the Blues' star man - but who else caught the eye?
Scroll down and click through the pages to see how chief sports writer Neill Allen rated Kenny Jackett's troops’ performances at Fratton Park.
1. Craig MacGillivray - 7
Barely challenged but saw off everything with ease Photo: PinPeP
2. Callum Johnson -
Comfortable defensively and always good attacking outlet Photo: PinPep
