Pompey made a swift return to winning ways after stunning Oxford with three goals inside the opening seven minutes.
They took the lead when Harry Clout sent in a cross that was headed home by Koby Mottoh at the back post.
And Mottoh was involved again as the advantage was doubled just moments later, turning back a corner for Maxwell Hurst (pictured) to convert.
But the Blues were not done and just seconds later, Hurst’s close-range finish secured a 3-0 Merit League victory.
Lead professional development phase coach Sam Hudson said: “It was an incredibly fast start and we’d asked the players for a reaction to the heavy defeat to Swindon the previous week.
“They answered that call emphatically – to go 3-0 up after seven minutes is unheard of and it could have been more because we also missed a good chance during that period.
“We pressed really well with intensity and aggression, while tactically the lads were absolutely spot on.
“They got their roles just right and we were getting defenders high up the pitch to pin Oxford right back.
"To go 3-0 up after seven minutes is unheard of and it could have been more because we also missed a good chance during that period."
“All of the goals came from that pressing and the ball didn’t go into our defensive third much. It was one-way traffic.
“Our opponents changed things and went a bit more direct, so we had to adapt to deal with that and initially lost some of our rhythm.
“But we were still relatively comfortable and it was then fairly even after the break, with both teams having a few chances.
“Malachi made a particularly strong save when we were defending a corner and their keeper also made some stops.
“There were not many more clear-cut opportunities, though, and our block was able to frustrate Oxford as the wind picked up, which proved a challenge.
“The game almost felt like it was done within 10 minutes of the second half and just as pleasing as our fast start, was the fact we kept a clean sheet.
“We haven’t had many of them this season and I was pleased with our performance, which puts us in a good performance for the Youth Alliance Cup final at Fratton Park on Wednesday.
Pompey: Osei-Owusu; Quarm, Bosaka (Mullins 46), Fox, Laidlaw; Murray (Staight 64), Aston; Mottoh, Keteku (Singerr 55), Clout (May 42); Hurst
Tickets are on sale for Pompey's Youth Alliance Cup final against Preston on Wednesday (7pm kick-off). Click here to secure your seat in the South Stand.
