Pompey produced a fine second half performance as they returned to winning ways in style against Southend.
They were left frustrated by a stubborn Shrimpers side for much of the first half, only for John Marquis to convert Brandon Haunstrup's cross on the stroke of the interval.
Ellis Harrison angled home a second goal following the restart and, after Brandon Goodship had struck for the visitors, added a penalty following a foul on Sean Raggett.