Marc McNulty bagged a hat-trick as Portsmouth won 6-0 and condemn struggling York to a seventh straight defeat.
Sheffield United loanee McNulty produced three sublime finishes, with Ben Davies and academy duo Ben Tollitt and Conor Chaplin completing the goal feast.
York's one-time Champions League winner Jonathan Greening was sent off on the cusp of half-time after a elbowing Portsmouth skipper Michael Doyle, sparking a goal rush after the break.
After a goalless first period in the Sky Bet League Two tussle, Portsmouth surged 2-0 up within seven second-half minutes.
Firstly Davies' drilled cross evaded everyone and found the net, then McNulty sidefooted Enda Stevens' flash across the box into the corner.
McNulty made it 3-0 after a lovely move involving Kyle Bennett and Davies - the frontman given an easy task of powering in from inside the box, before completing his treble with a stylish clipped finish.
Substitute Tollitt netted his first professional goal before teenager Chaplin slid in a sixth - to end Portsmouth's five-game winless run, York tumbling into the relegation zone.