Terry McPhillips admitted Pompey made Blackpool pay for their defensive relapses.
Ronan Curtis was at the double to give Kenny Jackett’s troops a 2-1 victory at Bloomfield Road on Saturday.
Both of the Irishman’s goal were similar, coming via Oli Hawkins headers which Curtis met and finished beyond Tangerines keeper Mark Howard both sides of half-time.
Mark Cullen struck in the 81st minute to grab a consolation for the hosts.
Blackpool were playing their first game following Gary Bowyer’s resignation as manager last Monday.
Caretaker boss McPhillips conceded it has been a difficult week for the club.
And although he was disappointed in the manner Blackpool conceded, he saluted their response after going 2-0 down.
‘It’s been a difficult week and it’s not the result we wanted,’ McPhillips told the Blackpool Gazette.
‘We started ever so well for the first few minutes but after that, they were better than us in the first half.
‘The goals were soft. So was ours, to be fair. All three were bad goals to concede. We paid for our mistakes but our response was terrific.
‘Just before they score their second goal (Nathan) Delfouneso has a good chance.
‘But that’s football, isn’t it? If you score that you’re back in the game, but they go down the other end and it’s 2-0. It’s a mountain to climb from there.’