Like last week, Pompey fans will be indebted to David James for saving Simon Whaley's penalty and making another superb stop from Neil Mellor's curling effort.
The first half was a bore as neither team could find a way through. Pompey were playing the better football and the closest we came to an goal was through Sulley Muntari's free kick that was tipped over by Lonergan. Hreidarsson fired into the side netting as Preston's Whaley looked dangerous for the hosts.
Despite looking the more dangerous side at the end of the first half, it was Alan Irvine's team that dominated as Pompey couldn't keep possession despite Harry's decision to revert back to the 4-3-3 formation.
Jamo was forced into a few good saves before Distin fouled Billy Jones in the box. Simon Whaley stepped up to take the penalty but his strike was poor and England's number one got down easily to save the spot kick and deny Preston the lead.
The home side continued to press as the Portsmouth players couldn't keep possession and were toothless up front because Kanu was fading whilst Kranjcar and Utaka couldn't controll the ball on the wings.
Papa Bouba Diop was singled out by fans as he couldn't pass wind today whilst our usually solid centre back partnership were forced into hurried clearances and long balls far too often.
James then stretched his arm to save Neil Mellor's effort that was curling into the net as Preston continued to pile on the pressure as Pompey kept giving the ball away. I'm sure I wasn't the only Pompey fan who would have taken a replay there and then as it looked like we were going to become the next side to be dumped out of the FA Cup by lower league opposition.
However, in the final minute of stoppage time Niko Kranjcar's corner caused panic in the Preston box and Darren Carter rifled his attempted clearance into his own net and send the Pompey fans wild.
I can't remember the last time we had such a huge slice of luck like that and the result is very cruel on Preston who outbattled and outplayed us in the second half.
However it's these sorts of things that makes me believe that maybe this is fate and it could really be our year. If we can avoid Manchester United and Chelsea in the draw tomorrow then I fancy our chances of going to Wembley, so long as we improve on what was a poor performance today.
I have sympathy for Preston fans but the bottom line is that we're in the quarter-finals of the FA Cup and this is the best chance we'll have of getting to Wembley.
Pompey Player Ratings
David James: 8 - Vital saves kept us in it despite some poor kicking.
Glen Johnson: 7 - Coped quite well with Whaley.
Sol Campbell: 6 - Strong but poor passing.
Sylvain Distin: 6 - Not a great return to the side but had the flu according to Harry.
Hermann Hreidarsson: 6 - Solid showing.
Sulley Muntari: 6 - Good free kick but no major influence in midfield.
Lassana Diarra: 6 - Relatively quiet.
Papa Bouba Diop: 5 - Constantly gave the ball away.
John Utaka: 6 - His pace should have caused more problems.
Niko Kranjcar: 6 - Wasn't allowed to weave his magic.
Kanu: 7 - Held the ball up well but faded as the game went on.
Substitutes
Jamie Ashdown
Lauren
Lucien Aubey
Richard Hughes
Milan Baros: N/A - Only had 15 minutes to change things.