For 24 minutes, Pompey were offered numerical advantage in their battle for parity against Sunderland.
Yet Kenny Jackett admitted the Blues didn’t threaten their 10-man Stadium of Light hosts sufficiently considering the beneficial circumstances.
It was Alim Ozturk’s mis-timed challenge on Gareth Evans which earned the central defender his marching orders on 66 minutes.
Sunderland boss Jack Ross subsequently announced he will appeal Andy Woolmer’s decision, potentially making him available for Thursday’s second leg.
Regardless, Pompey didn’t make that helping hand count, with Black Cats keeper Jon McLaughlin not asked to produce a save in the 1-0 defeat.
On occasions this season, Jackett’s men have ruthlessly exposed 10-men against Sunderland at Fratton Park and at Fleetwood.
But not so in Saturday night’s play-off semi-final first leg.
He said: ‘We didn’t capitalise on Sunderland going down to 10 men.
‘We moved the ball around at the back to a degree, some of our passing was good up to the box, but similarly up and around the box we couldn't’ get the final pass right.
‘During that period there was Viv trying to put Clarkie in and overhit it, once where O’Nien defended very, very well and probably four corners where the ball was bouncing around in the box, but fair play to Sunderland, they found a way of getting it out.
‘You are looking to try to get yourself back in the game but it didn’t happen against 10 men.
‘It’s evenly-balanced. We’ve the home leg to come, we’re a goal behind, but are capable of getting that back and look forward to the challenge now.’
Former loanee Chris Maguire’s stunning volley separated the sides in a poor spectacle.
The closest the Blues came to levelling was Gareth Evans’ free-kick, following that Ozturk foul, which struck the bar.
Overall, though, the Blues barely threatened throughout with their attacking play.
Jackett added: ‘In the first half we were the stronger side, but couldn’t get our delivery right.
‘We came out of good areas too many times and turned away. We didn’t have the explosiveness we usually have.
‘We needed that yard to get away and to put good balls into good areas. Gareth Evans, aside with a couple of good strikes, it was difficult for us going forward.
‘Similarly, we competed, we battled well, and we defended well, it was a good quality strike from Maguire which got their noses in front, but it’s evenly-balance for Thursday.
‘For all of our strength and competition, we couldn't find that one-v-one situation, couldn’t get away from people, couldn’t quite find that pass.’