Pompey picked up their first Fratton Park success of 2018 and closed in on the play-offs with a comprehensive victory over Oxford.
The Blues' delivered an ultimately-convincing 3-0 win after weathering pressure to grab their second successive clean sheet and move to within two points of the top six.
A Kal Naismith opener was supplemented by two Brett Pitman finishes after the break, with Jamal Lowe providing the supply.
Those Pitman goals came after Alex Mowatt was sent off in the 63rd minute immediately after seeing his penalty hit the post.
Kenny Jackett missed the game through a family health issue, but that didn't affect the display as the Sky cameras broadcasted an entertaining affair.
Pompey made the breakthrough with the first opening of the game after four minutes.
Dion Donohue delivered the corner which was met by Matt Clarke's head and prodded home by Naismith a few yards out.
The reply from the away side came after 21 minutes when James Henry cracked the bar with a lovely 20-yard hit.
Pompey were on top, though, and Pitman's outstretched leg couldn't turn in Lowe's cross after 25 minutes.
Home shouts for a red card for Rob Dickie weren't heeded three minutes later, after he hauled down Pitman, who was clear.
The ref gave the U's defender a yellow.
Luke McGee's outstretched arm tipped Malachi Napa's 25-yard drive around the post after 32 minutes.
The resulting corner saw McGee react well to keep out Napa's header, with Pitman then clearing off the line.
Oxford had turned the game's dynamic on its head and Dickie headed wide five minutes before the break as they finished much the stronger.
The second half sprung to life after 61 minutes after the visitors won a penalty, with Clarke penalised for a foul on Dickie.
Mowatt sent McGee the wrong way but saw his shot come back off the post, and then made matters far worse by slapping Nathan Thompson and being sent off.
Pitman then put daylight between the sides after 69 minutes as he thumped home his finish from a peach of a Lowe cross.
Lowe produced a lovely shot on the turn which was saved by Simon Eastwood after 78 minutes.
That didn't matter two minutes later, though, when Lowe rounded Eastwood and crossed under pressure from Ricardinho for Pitman to tap in his second.
Pompey were comfortable through four minutes of stoppage-time to ensure cheers and a Fratton feelgood factor on the final whistle.