The final scoreline suggests the win at Fratton Park was a comfortable one for the hosts – and one they dominated from start to finish.
However, it was anything but, with the displays either side of half-time completely contrasting.
The Blues went into the break with the match goalless and bottom-of-the-table Donny having the best chance of the game – only for Sean Raggett to clear the ball off the line.
It was enough to provoke a scattering of boos from the Fratton faithful at half-time as Pompey, who made three changes to the side that beat Burton 2-1 in midweek, failed to impose themselves on their visitors.
Yet Cowley’s side looked a completely different team after the restart and eventually ran out 4-0 winners.
Goals from Reeco Hackett, George Hirst, substitute Aiden O’Brien and Raggett saw them record their first back-to-back wins since November.
And afterwards Cowley revealed how he got a totally different performance from his players following the restart.
Speaking to BBC Solent after the game, he said: ‘It was a hard-fought first half.
‘We probably didn’t quite get the game plan to where we wanted it to be that first 20 minutes, which was too direct, too risk adverse.
‘I thought we had a better ending to the first half and found some rhythm.
‘Really, the message at half-time was just free the players up a bit, to be a little bit braver, a little more courageous on the ball.
‘We picked an attacking team, probably the most technical team that we’ve picked, I would say.
‘And you have to really commit to playing that way and I felt second half we did that.
‘You saw more rhythm and flow to our performance, particularly after we got the second goal.
‘I think you saw a confidence that maybe hasn’t been there, and yeah, I thought it was a really good second-half performance.’