Awful defending from two set-pieces saw John Mousinho’s men enter half-time 2-0 down and they rarely looked like finding a way back.
There was even a missed penalty from Colby Bishop in the 80th minute, after substitute Florian Bianchini had won it.
Then, out of nowhere, Adrian Segecic scored a cracker from outside the box and, coupled with 10 minutes of time added-on, a rejuvenated Blues set about trying to find an equaliser.
Connor Ogilvie was booked for simulation amid appears for a penalty, which John Swift struck the bar, yet there was to be no equaliser as they lost 2-1.
And here are our Pompey player ratings...
9. Callum Lang - 6
(Replaced by Florian Bianchini on 57 mins) Another devastating injury blow for the attacker, who collected an apparent hamstring issue at the start of the second half when he was fouled. Looked absolutely gutted, understandably so. Photo: Alun Roberts
10. Adrian Segecic - 7
After the heroics of Oxford United, was extremely anonymous in the first half. Then sprang to life midway through the second half and conjured up timely magic with a superb goal from nothing to ignite hopes of a point. Photo: Dan Istitene
11. Josh Murphy - 5
(Replaced by Thomas Waddingham on 70 mins) A surprise return to the side amid smoke and mirrors and, perhaps understandably, not at his best. There were flashes in the second half, yet didn’t have his usual fluency and some wayward shooting. Photo: Steve Bailey
12. Colby Bishop - 5
Had the opportunity to reduce the deficit after Bianchini won a penalty, but it was saved by Kovacevic low to his left. While dithered over one great first-half chance and was dispossessed as he shaped to shoot. Photo: Alun Roberts