Pompey fans were left fearing the worst when Wetherby Park was plunged into darkness by a power failure.
Their Emirates FA Cup first round tie at Harrogate Town finally got started 55 minutes late, only for the visitors to concede an early goal.
But stunning strikes from Brandon Haunstrup and Ronan Curtis ensured the non-league outfit were seen off.
And Kenny Jackett was pleased with the recovery, while also knowing there is plenty of room for improvement.
The Blues boss said: “Defending from set-pieces has been an Achilles heel for us this season and we struggled to deal with their centre-forward early on. It’s something we have to address.
“It looked like one-way traffic, we couldn’t get out and we couldn’t win the header. They got up a head of steam.
“But as the game wore on, my centre-backs grew in confidence and we scored two fantastic goals to get the win.
“We were away to Harrogate, who have had a good season so far and it was always going to be a difficult match.
"As the game wore on, my centre-backs grew in confidence and we scored two fantastic goals to get the win."
“I was delighted with the application our players’ showed. We weren’t dominant, but found a way to win. They dug in and worked hard for each other.
“Christian Burgess was one who had a few slips early on, but was really strong by the end of the match.”
Jackett was full of praise for the 616 Pompey supporters, who made the long trip north to pack the away section on a Monday night.
He said: “There was a fantastic turn-out and backing from our fans, despite the weather and the distance to travel.
“You also had the long delay, but they stuck with the boys right the way through and we really do appreciate that.”
Tom Naylor and Sean Raggett both limped off during the first half, while Ellis Harrison did not make the trip.
Jackett explained: “It was two muscle injuries from robust players and we’ll have to wait and see. It was a hamstring for Tom and an adductor for Sean. We obviously hope they’ll recover quickly.
“You’ve got a squad of players for a reason, though, and it could provide opportunities for others, while we’ve got a little spell without a game now.
“Ellis had a bad back and it’s reacted badly in the last 48 hours. We didn’t think it was a game to risk him in.”
Pompey will be at home in the second round, with National League North outfit Altrincham set to visit Fratton Park.
Jackett said: “It’s another difficult tie, but it’s at home. We should look at it as a good opportunity to get into the third round, without being over-confident.”