Kenny Jackett rued Pompey’s late set-piece defending as his side dropped two points at Bristol Rovers.
The Blues were well on their way to successive League One wins at the Memorial Stadium following goals either side of half-time from Gareth Evans and Ronan Curtis.
But the hosts conjured up a fightback to deprive Pompey of victory.
Alex Rodman reduced the arrears with 12 minutes remaining when the visitors failed to clear a free-kick.
Then in stoppage-time, Ross McCrorie hooked a corner onto his own crossbar, with the ball ricocheting off Craig MacGillivray and into the net.
Jackett was looking for his troops to see out a success – but they were unable to.
The Pompey boss said: ‘We put a lot of effort in and showed a lot of quality. W were 1-0 up at half-time and their keeper made a couple of great saves to stop us getting further ahead.
‘In second half, Rovers are always strong going into that end. They pinned us in and it looked like we weathered the storm.
‘We scored a cracking goal, it was a great cross from Marquis and header from Curtis at the far post.
‘Although I’d say you never feel comfortable because obviously you need to see it through, it’s two set-pieces – one goal from a wide free-kick and then a series of own goals for the second one.
‘Have we given away too many free-kicks? Should we then be perhaps be working zonally, where we too deep or not first to the ball?
‘Set-pieces have cost us some points.’