Pompey fired themselves to the top of League One with a 2-1 victory at Peterborough.
Oli Hawkins' first goal of the season and a strike from Jamal Lowe ensured the Blues leapfrogged the Posh to go to the summit of the division at London Road.
Matt Godden grabbed a late consolation for Steve Evans' side but Kenny Jackett's men held out to deliver all three points.
The first half was finely poised, with neither side creating any real clear-cut chances.
Jason Cummings came close to opening the scoring for the hosts on 26 minutes but his left-footed snap-shot was just off target.
Jason Naismith was also denied by a decent save from Craig MacGillivray in the 32nd minute following a neat move.
Pompey's best opportunities before the interval fell to Hawkins.
Four minutes before the break, Gareth Evans' cross picked out the striker inside the box, but his header failed to test home keeper Aaron Chapman.
The second half was nip and tuck before Hawkins broke the deadlock.
Ronan Curtis did brilliantly to beat Naismith, before picking out the ex-Dagenham & Redbridge marksman.
Hawkins' header wasn't the cleanest but it found the right-hand corner to give the Blues the lead.
And Jackett's troops doubled their advantage 15 minutes before full-time.
Hawkins' cross from the byline was headed down by that man Curtis to tee-up Lowe, and he kept his cool to slot home a first-time right-footed finish.
Peterborough snatched a late consolation through Godden's close-range strike in stoppage-time.
But Pompey held out well to clinch the win and move above Peterborough to the top of League One.
The Blues also stretched their unbeaten start to the season to eight matches.