Noe Pamarot blasted the visitors ahead with an eighth-minute piledriver, but hapless Brazilian Claudio Cacapa endured a personal nightmare as he was muscled off the ball by first Benjani Mwaruwari and then John Utaka as Pompey established a 3-0 lead before Newcastle had got their second wind.
Cacapa was put out of his misery when he was hauled off with just 18 minutes gone, and by that time, his side had grabbed a lifetime when Sol Campbell deflected the ball into his own net.
However, any hopes of a fightback died when Niko Kranjcar's 70th-minute free-kick eluded Steven Taylor, Abdoulaye Faye and then stand-in keeper Steve Harper to cement the win.
"You come to St James' Park and it is a difficult place to come - they get great support - and I just felt it was important we did not give anything away early on.
"The system we play, we have got an extra man in the middle of the park and they were going to get out-numbered in there, so I felt it was important we passed the ball and made them change their system or drag a wide man in.
"That was something we spoke about all week, and we did it to perfection - and the goals were absolutely fantastic."