Pompey were denied victory by a late goal for the second successive League One match as they were held to a 1-1 draw by Oxford at Fratton Park.
Matty Taylor's back post header on 90 minutes ensured Kenny Jackett's men were forced to settle for a point against the U's.
Gareth Evans' 58th-minute penalty looked to have put the hosts on the way to all three points.
However, just as in the draw at Bristol Rovers last time out, Pompey missed out on victory by Taylor's late header.
Pompey were unchanged from the team that started the draw at Bristol Rovers last time out.
Both sides took a while to get into their strides in the blustery conditions before Pompey mustered the first real clear-cut opening on 16 minutes.
Former Blues goalkeeper Simon Eastwood was out quickly to thwart winger Ryan Williams, then John Marquis' goalbound strike on the rebound was blocked by John Mousinho.
Kenny Jackett's men were growing in confidence as the half progressed, creating another good opening on 27 minutes.
Gareth Evans fired into Marquis, with the forward pulling the ball back for Ronan Curtis. The Republic of Ireland international tried his luck just inside the area, only for Mousinho to get in the way of his strike.
The visitors, who were carrying a threat but lacking a cutting edge, nearly went in front in calamitous fashion in first half stoppage-time.
Defender Sean Raggett's goalline clearance after Mark Sykes' strike cannoned off the back of goalkeeper Craig MacGillivray. But, fortunately for Pompey, it trickled just wide of goal.
Pompey came racing out of the traps after the restart, with Curtis going agonisingly close to opening the scoring on 50 minutes.
Winger Ryan Williams slipped in the Republic of Ireland international, only for his fizzing drive crashed against the crossbar.
But the Blues did take the lead eight minutes later. Ben Close was brought down by substitute Elliott Moore in the area after a sweeping move, with a penalty awarded. And Evans made no mistake, smashing past Eastwood in the U's goal.
The home side were buoyed after going in front with both Williams and Evans forcing the opposing goalkeeper into saves in the five minutes that followed.
Australian winger Williams then missed a good opportunity to double Pompey's advantage. He latched onto a goal-kick from MacGillivray, although his clever chipped attempt drifted just over the crossbar.
Just as it looked as though the Blues would wrap up all three points, Taylor headed home James Henry's cross at the back post on 90 minutes.