The Blues departed Lancashire with a hard-fought 1-1 draw against a side lying fourth before this afternoon's League One encounter.
Yet, disappointingly, when they finally broke the deadlock on 62 minutes through Oli Hawkins, it lasted just two minutes.
Hawkins' third goal in three matches put Pompey in pole position, only for Michael Ihiekwe to swiftly level from Sean McConville's free-kick.
Ronan Curtis twice struck the woodwork, while Craig MacGillivray saved Billy Kee's first-half penalty.
And Jackett was weighing up his emotions following the 1-1 outcome.
Pompey's boss said: '˜I have mixed feelings.
'˜We have come a long way for a 1-1 draw,Â but the fact we scored the first goal and conceded so quickly afterwards is slightly disappointing.
'˜I thought for the opening 20-30 minutes we looked strong. We did need to score in that period, we didn't put our chances away, while Ronan (Curtis) had a good header and hit the far post.
'˜Then there are two major incidents, the penalty where Craig has atoned for his mistake with a fantastic save '“and the free-kick which has got them the equaliser.
'˜I thought at the start of the second half for 15 minutes we looked strong, got the goal in the period and were obviously looking to go from strength to strength to get that win.
'˜But then we conceded straight away, and that is disappointing.'